Identifying Sentence Errors
Correct Answer: D
The error in the sentence is (D): the pronoun "their" in the phrase "of their" should be "it" because the pronoun refers to the singular noun "starling." Note that the verb following "starling" is singular, forcing one to recognize that the noun "starling" is singular. The correct sentence reads: The starling is such a pest in rural areas that it has become necessary to find ways of controlling the growth of its population.
(from the October 17, 1998 test)