Which of the following sets of data is bimodal?
A {2,3,4,4,5,6,7,7,8}
B {2,2,3,3,4,4,5,5,6,6}
C {2,3,4,4,4,5,6,7,8}
D {2,2,3,3,4,4,5,6,7,8}