Which choice completes the text so that it conforms to the conventions of Standard English?
A
digest
B
will digest
C
to digest
D
digesting
Explanation
Correct answer: C.
Choice C is the best answer. The convention being tested is the use of nonfinite verb forms within a sentence. Working together with the finite verb "need," the nonfinite to-infinitive verb "to digest" is correctly used to form a subordinate clause that describes what the reindeer need.
Why the other choices are wrong
Choice A
Choice A is incorrect because the verb "digest" (in either its finite or nonfinite form) can’t be used in this way with the finite verb "need."
Choice B
Choice B is incorrect because the finite verb "will digest" can’t be used in this way with the finite verb "need."
Choice D
Choice D is incorrect because the nonfinite participle "digesting" can’t be used in this way with the finite verb "need."