Why would you need to read your essay several times when editing it? you may keep starting and stopping. you may not catch all of the errors in one pass. you need to pay attention to each sentence.

true. the definition explains it: a word or phrase that modifies or qualifies an adjective, verb, or other adverb or a word group, expressing a relation of place, time, circumstance, manner, cause, degree, etc. this is a dictionary definition that i have looked up in a dictionary.

b is the answer for this question.