If c and d are unique prime integers, which of the following must be even?
Pick:
A) c−d
B) 2c−2d
C) c−2d
D) 2c−d
E) cd^2
Any number multiplied by 2 has to be an even number   Answer 2c−2d
<result>B</result>
If c and d are unique prime integers, which of the following must be even?