Hi,
Pronoun ambiguity in GMAT is not as objective as other error types such as SV number agreement errors, modifier errors, verb tense errors, parallelism errors, idiom errors are. We must not eliminate answer choices solely based on pronoun error right in the beginning of the process of elimination. Our approach should be:
a.
Understand the meaning of the sentence and determine the logical antecedent. Ensure that the pronoun-antecedent pair agrees in number.
b.
Determine if there is ambiguity in pronoun reference: Find if the pronoun can refer to any other noun.
Is there another noun (in same number) that plays similar role as the logical antecedent does? Yes -> ambiguity.
Is there another noun (in same number) that is closer to the pronoun than the logical antecedent? Yes -> ambiguity
c.
If there is pronoun ambiguity, then first eliminate answer choices with known objective errors - SV, verb, parallelism, modifiers, idioms. Use this ambiguous pronoun error as the last basis for elimination.
Fossils of the arm of a sloth found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of the Greater Antilles Islands.
Since pronoun "it" is singular, here are the possible antecedents - the singular nouns
"¢ Arm
"¢ Sloth
Notice here that both nouns play similar roles in the sentence - they describe the fossils. Thus, structurally they are at the same level in the sentence. Thus, even though it does not make logical sense for "it" to refer to "arm" since arm cannot be the mammal, structurally it still creates an ambiguity.
Since the pronoun analysis shows an apparent pronoun ambiguity, let us first eliminate the answer choices based on other more objective errors:
Choice A - Incorrect - comma + and used to combine two verb-ed modifiers - found... & dated.
Choice B - Incorrect - SV-Number Error - Plural noun fossils: Singular verb has been dated.
Choice C - Incorrect - SV-Number Error - Plural noun fossils: Singular verb was found.
Choice D - Correct - The pronoun ambiguity error has been corrected by replacing the pronoun with the antecedent to eliminate the pronoun usage altogether.
Choice E - Incorrect - SV-Number Error - Plural noun fossils: Singular verb was dated.
So in this sentence, we went purely by the meaning and determined the correct choice by using other errors - SV number error in this case. All choices except Choice D are eliminated. Choice D is the correct answer. It no longer has pronoun ambiguity error because the pronoun has been replaced with the noun/antecedent - sloth. More importantly, it does not make sense to say that "Fossils made the sloth the earliest known mammal". In fact it is the fact that these discovered fossils are so old that has made the sloth the earliest known mammal. This relationship has been clarified in choice D.
Now coming to the second sentence: The teacher included pronoun handout in the grammar folder so that the students can refer to it later.
This sentence is correct because "it" has only one logical noun antecedent "pronoun handout" here. Pronoun handout is the main point of focus here. Even if we delete "in the grammar folder", the sentence will still convey the same meaning. Per the meaning, the teacher wants the students to look at the pronoun handout. That is the reason why she included it in the grammar folder. If the teacher wanted to refer to the grammar folder later, then there would have been no need to mention the inclusion of the pronoun handout. Hence, it is very important to understand the logical meaning of the sentence to determine the logical antecedent of the sentence.
The doctors have managed to significantly reduce the mortality rate and the public is very pleased with them for doing it.
Pronouns can only refer to nouns and other pronouns. You are correct in saying that "it" here refers to "significantly reduce the mortality rate". Thus means that "it" is referring to the action of reducing the mortality rate, i. e. the verb. Since pronouns can only refer to nouns and other pronouns, reference of "it" is incorrect here.
