If x is an odd integer, which of the following must also be odd?	Choose the correct choice from the following.
A) 2x + 4
B) x + x
C) 3x + 3
D) 2x + x
E) x^2 + 1
Odd + odd = even   Odd + even = odd   Odd*odd = odd   Odd*even = even   On checking each option   A. 2x + 4   2x = even, 2 x + 4 = even + even = even.   B. x + x   Odd + odd = even. This will be even   C. 3x + 3   3x = odd, 3x + 3 = odd + odd = even   D. 2x + x   2x = even, 2x + x = even + odd = odd   E. x^2 + 1   x^2 = odd, x^2 + 1 = odd + odd = even   Correct option: 2x + x
<result>D</result>
If x is an odd integer, which of the following must also be odd?