Identify the correct sentence.
a. one of the boys on the baseball team lost his or her sweater.
b. one of the boys on the baseball team lost him sweater.
c. one of the boys on the baseball team lost their sweater.
d. one of the boys on the baseball team lost his sweater.

D. One of the boys on the baseball team lost his sweater.

Explanation:

From the four choices provided in the question, the correct answer is the fourth sentence "One of the boys on the baseball team lost his sweater."

Option A is wrong in the use of "his or her" for it is clearly stated that it is "one of the boys". So there is no need of "her' in the sentence because the phrase "one of the boys" explicitly denotes a male, masculine gender.

Option B is wrong in its use of the word "him" to show the possession of the sweater. Him is a pronoun and not a possessive form of the noun.

Likewise, Option C is wrong in the use of the possessive form "their" for the sentence clearly mentions "one of the boys" which means a singular masculine gender.

Thus, the correct sentence is D. One of the boys on the baseball team lost his sweater.

is there a answer choice?

debating and finalizing the detail of the policy