Answer:
The answer is indeed D. an expository essay.
Step-by-step explanation:
An analytical or expository essay consists of an idea being presented in a clear and short manner after due research. There must be an investigation of the idea, collection and analysis of evidence to do so. This kind of essay may simply aim for the clarification of an idea, instead of trying to defend an argument or opinion about it. Thus, it is usually unbiased, as opposed to an argumentative essay.