The simplest way to solve this is to choose numbers for x. Try to choose numbers that you believe will produce differing answers. For example:
If x = 2
then quantity A is 2 + 2 = 4
and quantity B is 22 = 0
giving us an answer of A. But let's try other numbers to get another answer:
If x = 2
then quantity A is 2 + 2 = 4
and quantity B is 22 = 4
giving us an answer of C.
Since we were able to generate two different answers, the real answer is D.
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