Meaning: To 'complete' means to finish or bring to an end.

Wrong options:

• already: 'Already' is an adverb that indicates something has happened before now, which does not fit as it does not describe the action of the process.
• exceed: 'Exceed' is a verb that means to go beyond a limit, which does not relate to the completion of a process.
• inner: 'Inner' is an adjective that describes something internal, which does not fit the context of a process being completed.
• this: 'This' is a demonstrative pronoun that refers to something specific, but it does not convey an action related to the process.
• complete: 'Complete' is the correct answer, so it cannot be a wrong option.
• change: 'Change' is a verb that indicates making something different, which does not fit the context of finishing a process.

Correct answer: already

Explanation: The word 'already' functions as an adverb indicating that the action of completing the demographic transition has occurred prior to the present time. This fits well with the context of discussing nations that have completed the transition.

Meaning: 'Already' means before the present time or earlier than expected.

Wrong options:

• complete: 'Complete' is a verb that does not fit as it does not describe the timing of an action.
• exceed: 'Exceed' is a verb that means to go beyond a limit, which does not relate to the completion of a process.
• out: 'Out' is a preposition or adverb that does not convey the timing of an action in this context.
• inner: 'Inner' is an adjective that describes something internal, which does not fit the context of timing.
• this: 'This' is a demonstrative pronoun that does not indicate timing and is not appropriate here.
• change: 'Change' is a verb that does not relate to the completion of the demographic transition.

Correct answer: out

Explanation: The word 'out' fits grammatically as it is part of the phrasal verb 'carry out,' which means to perform or execute a process. Contextually, it aligns with the idea of nations still in the process of demographic transition.

Meaning: To 'carry out' means to perform or execute a task or process.

Wrong options:

• already: 'Already' is an adverb that indicates something has happened before now, which does not fit as it does not describe the action of performing a process.
• exceed: 'Exceed' is a verb that means to go beyond a limit, which does not relate to the execution of a process.
• inner: 'Inner' is an adjective that describes something internal, which does not fit the context of performing a process.
• this: 'This' is a demonstrative pronoun that does not convey an action related to the process.
• complete: 'Complete' is a verb that does not fit as it does not describe the action of carrying out a process.
• change: 'Change' is a verb that indicates making something different, which does not fit the context of executing a process.

Correct answer: this

Explanation: The word 'this' serves as a demonstrative pronoun that refers back to the transition mentioned earlier in the sentence. It fits grammatically and contextually as it emphasizes the specific transition being discussed.

Meaning: 'This' is used to refer to a specific thing or idea that is close in context, in this case, the demographic transition.

Wrong options:

• already: 'Already' is an adverb that does not refer to a specific transition and does not fit in this context.
• exceed: 'Exceed' is a verb that does not relate to the concept of a transition and does not fit grammatically.
• out: 'Out' is a preposition or adverb that does not refer to a specific transition and is not appropriate here.
• inner: 'Inner' is an adjective that describes something internal, which does not fit the context of discussing a transition.
• complete: 'Complete' is a verb that does not refer to a specific transition and is not suitable in this context.
• change: 'Change' is a verb that indicates making something different, which does not fit the context of identifying a transition.