Which aspect is most important in a writer? A. to have a desire to write B. to have a thorough knowledge of grammar C. to be well educated D. to have a separate room to sit and write

I would say B. to have a thorough knowledge of grammar

Option A. The aspect that is most important in a writer is to have a desire to write.

Explanation:

In order to be a writer that person needs to foremost have a desire to write. Whether it involves creative writing, in which the writer needs to have inspiration in order to create a story, or even if it is research or academic writing, the person needs to have the motivation and desire to sit down and start to write. Writing is not an activity that one person can do involuntary or without putting any type of effort in it, and is because of this that a willingness to write is the first thing a writer needs to have. The writer can always improve his/her knowledge of grammar, or become more educated if that is important to him/her, but all of that would not matter if that person does not have the power and desire to sit down and start writing.