Meaning: 'Evolving' means developing gradually, indicating that the stock of dwellings is in a state of change.

Wrong options:

• height: The word 'height' is a noun that refers to the measurement of something from base to top, which does not fit the context of describing the state of dwellings.
• compared: 'Compared' is a past participle that does not convey the ongoing nature of change required in this context.
• examines: 'Examines' is a verb that indicates an action of investigation, which does not fit as it does not describe the state of the stock of dwellings.
• article: 'Article' is a noun that refers to a written composition, which does not fit grammatically or contextually in this sentence.
• proportions: 'Proportions' is a noun that refers to a part or share of a whole, which does not describe the state of the stock of dwellings.

Correct answer: proportions

Explanation: The term 'proportions' is a plural noun that fits grammatically as it refers to the parts of couple families with children in relation to the whole. It is contextually appropriate as it discusses the decreasing share of these families.

Meaning: 'Proportions' refers to the relative amounts or shares of something, in this case, the share of couple families with children.

Wrong options:

• evolving: 'Evolving' is a verb that describes a process of change, which does not fit as it does not refer to a quantity or share.
• mainly: 'Mainly' is an adverb that indicates the primary focus, which does not fit as it does not refer to a quantity or share.
• examines: 'Examines' is a verb that indicates an action of investigation, which does not fit as it does not refer to a quantity or share.
• height: 'Height' is a noun that refers to the measurement of something from base to top, which does not fit in this context.
• article: 'Article' is a noun that refers to a written composition, which does not fit as it does not refer to a quantity or share.

Correct answer: mainly

Explanation: The word 'mainly' is an adverb that fits grammatically as it modifies the phrase 'couple only and lone person households,' indicating that these types of households are the primary focus of the discussion. It aligns with the context of describing the composition of households.

Meaning: 'Mainly' means primarily or chiefly, indicating the predominant types of households being discussed.

Wrong options:

• evolving: 'Evolving' is a verb that describes a process of change, which does not fit as it does not modify the types of households appropriately.
• examines: 'Examines' is a verb that indicates an action of investigation, which does not fit as it does not serve as a modifier in this context.
• height: 'Height' is a noun that refers to the measurement of something from base to top, which does not fit as it does not modify the types of households.
• proportions: 'Proportions' is a noun that refers to parts of a whole, which does not fit as it does not serve as a modifier in this context.
• article: 'Article' is a noun that refers to a written composition, which does not fit as it does not modify the types of households.

Correct answer: article

Explanation: The word 'article' is a noun that fits grammatically as it serves as the subject of the sentence, indicating what is being discussed. It is contextually appropriate as it refers to the written piece examining household changes.

Meaning: 'Article' refers to a written composition, typically in a publication, that discusses a specific topic.

Wrong options:

• evolving: 'Evolving' is a verb that describes a process of change, which does not fit as it does not serve as a subject in this context.
• mainly: 'Mainly' is an adverb that indicates the primary focus, which does not fit as it cannot serve as a subject.
• examines: 'Examines' is a verb that indicates an action of investigation, which does not fit as it cannot serve as a subject.
• height: 'Height' is a noun that refers to the measurement of something from base to top, which does not fit as it does not serve as a subject in this context.
• proportions: 'Proportions' is a noun that refers to parts of a whole, which does not fit as it does not serve as a subject in this context.