I believe the correct answer might be B.
If you are going to write a paper about human anatomy, it would be useful to have a biology dictionary (option D) because there you might find all the concepts related to the topic and their proper definitions. A regular dictionary would be more general and you may not find all the concepts you need to write about such specific topic.
Answer:
B: the students are the subject of the sentence and the doers of the verb.
Explanation:
A, C, and D are still passive because the subject is being acted upon.
D. Second
Connecting or transitional words