31, 29, 24, 22, 17, ?	Choose the correct answer:
A) 15 B) 23 C) 13 D) 25 E) 28
This is a simple alternating subtraction series, with a pattern -2, -5, -2, -5 ....   15nswer : 15.
<result>A</result>
31, 29, 24, 22, 17, ?