Task: Question Answering
Input (English): Question: Of the final grades received by the students in a certain math course, 1/5 are A's, 1/4 are B's, 1/2 are C's, and the remaining 30 grades are D's. What is the number of students in the course?

 Option A:  80

 Option B:  110

 Option C:  160

 Option D:  600

 Option E:  400
Output (English): Option D