Which choice best describes a reason a writer uses commentary? bc
To provide explanation and analysis of evidence
To organize paragraphs by when events happened
To condense several ideas into a few sentences
To synthesize main ideas from the text

To provide explanation and analysis of evidence.

Explanation:

A commentary is a detailed explanation from the author's side, the expression of his/her opinions about whatever is being discussed or referred to. In other words, we can say that a commentary is when an author provides an explanation about the events or a situation.

One of the primary reasons why writers use commentaries is to provide explanations and also their analysis of evidence that's been provided or given. This allows the writer a chance to express his/her opinions about that particular point or the point made or argued about in a text.

Thus, the correct answer is the first option.

quite an interesting way to teach topic sentences, because the answer to this question is the best definition of a topic sentence that one can present, it is as if answering the questions taught you how to do it, this is some real teaching, it is terribly well-done.

the topic sentence in this paragraph is:

topic sentences writers stay on track and keep a paragraph from becoming an aimless collection of sentences about an idea.

which incidentally tells you what a topic sentence should be.