1.  28 25 5 21 18 5 14
A. 11 5
B. 10 7
C. 11 8
D. 5 10
E. 10 5

Answer: Option A

Explanation:

This is an alternating subtraction series with the interpolation of a random number, 5, as every third number. In the subtraction series, 3 is subtracted, then 4, then 3, and so on.