Respuesta :
D. the reader. The reader will always be the one you're writing for, since the idea of writing, especially academic writing, is usually meant for others to read.
The correct answer is:
D.The reader.
Even though the teacher is reasonably the actual audience for an academic paper, if we write an essay with only an instructor in mind, we´ll probably leave out information assuming that the person reading it knows enough about it. By addressing an essay as if it was done for an intelligent yet uninformed reader, we can communicate more effectively.