This is indirect characterization because it SHOWS, rather than tells.
Here are two examples:
Indirect: Erica stomped her foot and flew out of the room.
This shows that she is angry, rather than just tells.
Direct: Erica was so angry she stomped her foot and flew out of the room.
This just tells you she's mad.
D. Students think that the most important subjects are those that will be useful after graduation
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.
Wait is this a question or what?