Question

Select the noun phrase to complete the sentence.

Answer 1

A noun phrase is a phrase which has a noun or a pronoun as the nucleus and, gramatically, functions as a noun.

Considering this, we can conclude that the correct answer is C: "a relatively short time period" because the nucleus of that phrase is the noun "period".

The rest are not possible options because both A and B are independent clauses which do not complete the sentence but add new independent information, and D is not a noun phrase.

Answer 2

C-, a relatively short time period.