A is the correct answer. This applies to most, if not every, essay.
B implies you should only use one source, something that would, more often than not, hurt your case no matter the subject.
C This answer assumes what you have written in your journal. You are not a valid source, nor do you have every piece of information on hand.
D While teachers can help you pick your topic, it is best to use your own ideas and creativity when writing.