10, 50, 13, 45, 18, 38, ?.
What a number should replace the question mark?  Choices:
A) 34
B) 27
C) 25
D) 46
E) 51
25   25   There are two alternate sequences: start at 10 and add 3, 5, 7;   start at 50 and deduct 5, 7, 9.
<result>C</result>
10, 50, 13, 45, 18, 38, ?.
What a number should replace the question mark?