Answer:
C. ab
Explanation:
If a is a nonzero interger and b is not an integer, a + b, a - b or 2a - b will be not an integer. For example, if a = 2 and b = 0.5, then:
a + b = 2 + 0.5 = 2.5
a - b = 2 - 0.5 = 1.5
2a - b = 2(2) - 0.5 = 4 - 0.5 = 3.5
Where 2.5, 1.5 and 3.5 are not integers.
However, ab could be an integer. In this example, we get:
ab = 2(0.5) = 1
And 1 is an integer.
Therefore, the answer is ab