Commentators don't know if Denny will try and become the first athlete

Official Explanation:

Since the underlined portion of the sentence contains the word if, check whether this word is used correctly. The underlined portion of the sentence also contains the phrase try and, so check whether this phrase is used correctly. Because if is used for conditional statements, while whether is used for two possibilities, whether is the correct word to use in this sentence. This is an idiom error. The construction try and is the incorrect form of the idiom try to, so this is also an idiom error. Eliminate choice A for both idiom errors and look for any obvious repeaters. Choice B is an obvious repeater of the first idiom error because it contains the word if instead of the word whether, so eliminate choice B. Choice E is an obvious repeater of the second idiom error because it contains the construction try and instead of the correct construction try to, so eliminate choice E. Now evaluate the remaining answer choices individually, looking for reasons to eliminate each.

Choice C fixes both idiom errors by using whether and try to, and introduces no new errors, so keep choice C. Choice D fixes the second idiom error by using the correct construction try to, but does not fix the first idiom error because it uses the construction whether…or not which is incorrect because whether alone indicates that there are two possibilities. Eliminate choice D.

Alternatively, if it is difficult to spot the grammar rule the sentence is testing, another strategy is to identify an error from the answers by looking for either a 2/3 split or differences among the answers. Because three of the answer choices use the word whether and two of them use the word if, this difference is an indication to look for idiom errors.

Choice A: No. The word if is used instead of the correct word whether. The phrase try and is used instead of the correct phrase try to. Idiom.

Choice B: No. The word if is used instead of the correct word whether. Idiom.

Choice C: Correct.

Choice D: No. The phrase whether…or not is used instead of the correct word whether. Idiom.

Choice E: No. The phrase try and is used instead of the correct phrase try to. Idiom.

The correct answer is choice C.