Look at this series: 17, 24, 21, 28, ... What number should come next?	Choose the most appropriate option.
A) 33  B) 28  C) 32  D) 35  E) 39
Explanation:   This is a simple alternating addition and subtraction series. In the first pattern, 7 is added; in the second, 3 is subtracted.   Answer: Option 32
<result>C</result>
Look at this series: 17, 24, 21, 28, ... What number should come next?