4 GHz channel usage for a survey and voice deployment in the ETSI domain?

Which option will allow the maximum 2.4 GHz channel usage for a survey and voice deployment in the ETSI domain?

A.
1, 6, 11

B.
1, 5, 9, 13

C.
1, 6, 9, 14

D.
1, 6, 11, 14

Explanation: