When Preparing to Write an Essay, Should You Read a Textbook

When preparing to write an essay, should you read a textbook and, if so, which one(s) ?

A) There is no need to read a textbook. Your course materials and the lecture notes you have taken will provide all of the information that is needed to write the essay.
B) There is no need to read a textbook. You should use only primary sources, such as relevant statutes and case law.
C) You should read a textbook, but only that which has been recommended by your lecturer as required reading for the course, because that book contains all of the points that the lecturer expects to see in the essay.
D) You should read a range of textbooks, because each author will have selected different material and explained it in a different way, so there is a greater chance that you will grasp the issues needed to answer the question.