If q is an odd integer, which of the following must also be odd?  Choose the most appropriate option:  A) 6q + 4  B) q + q  C) 3q + 3  D) 2q + q  E) q^2 + 1
Things to keep in mind:   Odd + odd = even   Odd + even = odd   Odd*odd = odd   Odd*even = even   On checking each option   A. 6q + 4   6q = even, 6q + 4 = even + even = even.   B. q + q   Odd + odd = even. This will be even   C. 3q + 3   3q = odd, 3q + 3 = odd + odd = even   D. 2q + q   2q = even, 2q +q = even + odd = odd   E. q^2 + 1   q^2 = odd, q^2 + 1 = odd + odd = even   Correct option: 2q + q
<result>D</result>
If q is an odd integer, which of the following must also be odd?