Meaning: To 'celebrate' means to acknowledge or honor something as significant or positive.

Wrong options:

• sold: The word 'sold' is a past participle that refers to the act of selling, which does not fit the context of acknowledging life expectancy.
• enhance: The word 'enhance' is a verb that means to improve or increase, which does not fit as it does not relate to the social acknowledgment of life expectancy.
• does: The word 'does' is a verb that indicates action but does not fit as it does not convey the idea of celebration or acknowledgment.
• output: The word 'output' is a noun that refers to the amount produced, which does not fit in the context of social reasons for life expectancy.
• older: The word 'older' is an adjective that describes age but does not fit as it does not relate to the act of celebrating.
• young: The word 'young' is an adjective that describes youth, which is contrary to the context of discussing older generations.

Correct answer: older

Explanation: The term 'older' is an adjective that describes the demographic being discussed, fitting grammatically and contextually as it refers to the population that is increasing in life expectancy. It aligns with the context of mobilizing this demographic for economic productivity.

Meaning: 'Older' refers to individuals who have lived for a longer period of time, typically associated with senior citizens.

Wrong options:

• sold: The word 'sold' is a past participle that does not relate to describing a demographic and does not fit in this context.
• celebrated: The word 'celebrated' is a past participle that refers to acknowledgment but does not describe a demographic group.
• enhance: The word 'enhance' is a verb that means to improve, which does not fit as it does not describe a group of people.
• does: The word 'does' is a verb that indicates action but does not describe a demographic and is not appropriate here.
• output: The word 'output' is a noun that refers to production, which does not fit as it does not describe people.
• young: The word 'young' is an adjective that describes youth, which is contrary to the context of discussing older individuals.

Correct answer: enhance

Explanation: The word 'enhance' is a verb that fits grammatically as it indicates the action that older people can take to improve productivity. It aligns with the context of discussing how this demographic can contribute positively to their communities.

Meaning: To 'enhance' means to improve or increase the quality or value of something.

Wrong options:

• sold: The word 'sold' is a past participle that refers to the act of selling, which does not fit the context of improving productivity.
• celebrated: The word 'celebrated' is a past participle that refers to acknowledgment and does not fit as it does not indicate an action related to productivity.
• does: The word 'does' is a verb that indicates action but does not convey the idea of improving productivity.
• output: The word 'output' is a noun that refers to production, which does not fit as it does not indicate an action.
• older: The word 'older' is an adjective that describes age but does not fit as it does not indicate an action related to productivity.
• young: The word 'young' is an adjective that describes youth, which is contrary to the context of discussing productivity enhancement.

Correct answer: does

Explanation: The word 'does' serves as an auxiliary verb that fits grammatically to indicate that the increase in life expectancy correlates with an increase in output. It maintains the logical flow of the sentence, linking the two ideas effectively.

Meaning: 'Does' is an auxiliary verb used to form questions and negatives, and here it indicates that the increase in life expectancy results in increased productivity.

Wrong options:

• sold: The word 'sold' is a past participle that refers to the act of selling, which does not fit the context of discussing output.
• celebrated: The word 'celebrated' is a past participle that refers to acknowledgment and does not fit as it does not indicate a correlation with output.
• output: The word 'output' is a noun that refers to production, which does not fit as it does not serve as a verb in this context.
• older: The word 'older' is an adjective that describes age but does not fit as it does not indicate an action or correlation.
• young: The word 'young' is an adjective that describes youth, which is contrary to the context of discussing productivity.