If c and d are unique prime integers, which of the following must be odd?	Pick one
A) a−b B) a−2b C) 2c−2d D) 2c/2d E) c-d
The answer is C. Let's assume that a is an even prime integer and b is an odd prime integer, their subtraction results in an odd integer and an odd integer multiplied by an even integer yields an even integer.   Answer 2c−2d
<result>C</result>
If c and d are unique prime integers, which of the following must be odd?