Let x, y and z be distinct
integers, that are odd and positive. Which one of the following statements
cannot be true?
a. xyz^2 is odd
b. (x - y)^2 z is even
c. (x + y - z)^2 (x + y) is even
d. (x - y)(y + z)(x + y - z) is odd
In
option d), x-y is even. So, the product of the three terms is even.