7, 10, 8, 11, 9, 12, ?  Choose the correct option.
A) 13  B) 12  C) 10  D) 9  E) 8
This is a simple alternating addition and subtraction series. In the first pattern, 3 is added; in the second, 2 is subtracted.   Answer : 10.
<result>C</result>
7, 10, 8, 11, 9, 12, ?