What is the difference between a synecdoche and a metonymy?

Synecdoche refers to a thing and its parts. The best example is the use of the word “wheel” instead of “car”. As we know, a wheel is a car part. 

On the other hand, metonymy refers to a thing that is very much related to another thing. The easiest example we can use here is the word “crown” when used in some literature pieces means power.

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.