There are two groups of students in the sixth grade.

There are two groups of students in the sixth grade. There are 30 students in group A, and 50 students in group B. If, on a particular day, 20% of the students in group A forget their homework, and 12% of the students in group B forget their homework, then what percentage of the sixth graders forgot their homework?

A. 13%
B. 14%
C. 15%
D. 16%
E. 17%