GRE Sample Test 3 Quantitative Reasoning 2

The first two factors form a difference of squares:
$\left(\sqrt{3}+\sqrt{2}\right)\left(\sqrt{3}-\sqrt{2}\right)$ = $\sqrt{3}-\sqrt{2}$ = 3 - 2 = 1
The last two factors form a difference of squares:
$\left(\sqrt{7}-\sqrt{5}\right)\left(\sqrt{7}+\sqrt{5}\right)$ = $\sqrt{7}-\sqrt{5}$ = 7 - 5 = 2.
The multiply the 1 × 2 = 2