B can be any value, so the answer is D

I think the answer is B. We do not need the value of b as it can be cancelled out. Since b is on both sides whatever it’s value is it will cancel out. Leaving the side B greater than A.

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When we talk about "cancelling out" variables, we must be clear what we're actually doing.
To get "cancel out" the variable b, we need to divide both quantities by b.
However, since we don't know whether b is positive, negative or zero, we can't just divide both quantities by b.

For example, if b = 0, then the two quantities are equal.
If b = -1, then quantity A is greater
And, if b = 1, then quantity B is greater

Cheers,
Brent