Question

Which type of dictionary should you own for doing school work?

Answer 1

Since school is best considered as "preparing for college" you should use a college book. C

Answer 2

College-level dictionaries are designed to be conveniently handy, and conveniently shorten  without losing its sense, especially for school students aiming to attain college level of education.

Thereby, (C). "a College-level abridged dictionary" would be suitable.