Answer
a) is correct.
Work Step by Step
We have $$\overline P=\frac{W}{t}$$
Since $\overline P_A\gt\overline P_B$ and $t_A=t_B$, it follows that $W_A\gt W_B$; in the same amount of time, the amount of work done by engine A is greater than that done by engine B. Therefore, both b) and c) are incorrect.
Now if $W_A=W_B$, we will have $t_A\lt t_B$; engine A finishes the same amount of work more quickly than engine B. a) is correct.
