In the sentence below, a portion is highlighted in bold. This phrase may contain a grammatical error. Choose the option that correctly replaces the bolded phrase to make the sentence grammatically correct. If the sentence is already correct, select 'No improvement required'.

Paris continue to assert its dedication to environmental pacts and the pursuit of global stability.

The correct option is continues to assert its.

Step-by-Step Explanation:

1. Subject-Verb Agreement:
The subject of the sentence is "Paris", which is a proper noun referring to a single city (singular subject). Therefore, it requires a singular verb. The verb "continue" is plural, whereas "continues" is the singular form. Thus, "continue" must be changed to "continues".

2. Verb Form after Infinitive "to":
The particle "to" forms an infinitive verb phrase, which requires the base form of the verb (bare infinitive). Therefore, we must use "assert" instead of the conjugated form "asserts". "To assert" is grammatically correct, while "to asserts" is incorrect.

3. Possessive Pronoun vs. Contraction:
The word "its" (without an apostrophe) is the possessive form of the pronoun "it", which is appropriate here to show possession of "dedication". The form "it's" with an apostrophe is a contraction for "it is" or "it has", which does not fit grammatically in this context.

Combining all these corrections gives: continues to assert its.