Plz help idk which one it is

The correct answer is D. Clause

Explanation:

In grammar, a clause is a grammatical unit that contains a coherent idea or part of an idea and has a subject such as a noun, and a verb or action. These two elements make a clause differ from other elements such as a phrase. For example, the unit "They go to the mall" is a clause because it includes the subject "they" and the verb "go". Moreover, clauses that express a complete idea are known as independent, while those that are part of other sentences or need another sentence are dependent. According to this, the definition refers to a clause because only clauses have a subject and a verb, also, they can be complete sentences or part of these.

the answer should be b.

explanation:

it should be b because she researched before writing so it would be in past tense. "the author researches her subject before she had written the first draft.