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answer is C. here is how i do it:
remember that for a product to be even - one multiplier must be even.
st1. if d is 1 c can be anything hence insufficient
st2. same as st1. if d is 2 c can be anything.

together:

if c is odd, then from st1 d+1 must even. from st2 d+4 must be even (c is odd means c+2 is odd as well).
but d+1 and d+4 cannot be both even at the same time.
hence c cannot be odd. so c is even.