B. C. pitch and volume
D frequency
11. Mike invented a backpack to help protect students' backs when they carry
their books home from school. He showed his idea to some other students
and got their opinions. The students suggested some changes. What should
he do next?
A. revise his design
B. ignore the opinions of other students
C. forget about his design
D. keep showing his design to other students until he finds students who
like it