If a and b are positive, is (a^-1 + b^-1) less than (a^-1*b^-1)^-1
I chose D
D is not possible, because A is insufficient.
Try 4|2 and 0.5|0.25 respectively, both will give you different results.
I guessed C, because I ran out of time
Rewriting the expression in the first place might be clever:
(b+a)/(ab) < ab should be the same expression.