Solution to problem #1: West African Lungfish
Correct answer: C
(A) Incorrect
Singular vs. Plural: The word fish can be both singular and plural. In the original sentence, the singular verb uses signals that the word lungfish is singular, but the plural pronouns their and they signal that the word lungfish is plural. Both can’t be true at the same time, so the original sentence is incorrect.
Modifier: The adverbial modifier surviving long periods of dormancy logically follows from the lungfish’s ability to extract oxygen from air, not from the fact that it burrow(s) deep into muddy ground. It can survive dormancy because it has the ability to extract oxygen from air even when in dormancy.
(B) Incorrect
Singular vs. Plural: The plural pronoun their signals an intent to talk about multiple lungfish (or all lungfish). Many lungfish also have many lungs, so the sentence should refer to their primitive lungs, plural, not their primitive lung.
Modifier: Using their lungs to extract oxygen isn’t what directly allows the lungfish to burrow deep into the ground. Rather, the lungfish has the ability to burrow in general; it can survive long periods of this burrowing because it can use its primitive lungs to extract oxygen from the air.
Idiom: If given a choice between use lungs to extract or use lungs for the extraction of, choose use lungs to extract.
(C) CORRECTThe main verb, can survive, can be singular or plural: it can survive; they can survive. It is fine, then, to use the singular pronoun its to refer to the lungfish (when doing this for an animal, it’s generally considered that the sentence is referring to the species in general).
The modifiers are now correctly placed, clearly conveying the intended meaning: While the lungfish is burrowed underground, it uses its lungs to extract oxygen from the air above, and this action allows it to survive these long periods of dormancy.
It is permissible to use a hyphen to set off the final modifier, an ability known as “estivation.” The modifier is correctly referring to the noun before it, dormancy.
(D) Incorrect
Modifier: Using its lungs to extract oxygen isn’t what directly allows the lungfish to burrow deep into the ground. Rather, the lungfish has the ability to burrow in general; it can survive long periods of this burrowing because it can use its primitive lungs to extract oxygen from the air.
Parallelism: The parallelism marker and signals the need to make two words parallel: X and Y. In this sentence, the Y element is surviving. The X element is either can burrow or burrow, neither of which is parallel to surviving.
Idiom: If given a choice between use lungs to extract or use lungs for extracting of, choose use lungs to extract.
(E) Incorrect
Sentence Structure: The sentence has no main verb. It consists of a subject, the West African lungfish, and many modifiers.