Which pronoun correctly completes the following: "The pair of shoes lost (its, their) shine after a month"?

In the sentence "The pair of shoes lost (its, their) shine after a month," the correct pronoun is "its." This is because "the pair of shoes" is considered a singular noun phrase referring to a single unit—a pair. Pronouns used to refer to singular nouns need to match in number and gender, and "its" is the appropriate possessive pronoun for singular nouns.

Using "their" would imply a plural subject, which does not align with the singular nature of "pair." Hence, "its" effectively conveys that the shine belonging to the single pair of shoes diminished over time. This demonstrates the importance of ensuring pronouns correctly reflect the quantity and ownership referenced in the sentence.