$$Average\ speed=\ \frac{Dis\tan ce}{time\ taken}$$
What was Robin's Average speed for the entire drop

Statement 1
While driving from Townville to Villageton
Robin's average speed was 40 miles per hour while driving from villageton to Townvile Robin's average speed was 60 miles per hour.

Let the distance = D; between hours = 2D
Time = d/40 ( From Townsville to villageton )
= d/60 ( From Villageton to Townsville)
$$\frac{d}{40}+\frac{d}{60}=\frac{d}{24}$$
$$average\ speed\ =\frac{2D}{\frac{d}{24}}=2D\cdot\frac{24}{D}=\frac{48D}{D}=48$$
Statement 1 is SUFFICIENT.

statement 2
Distance from Townsville to Villageton is 120 miles, this is not enough to calculate speed because, distance is missing
Statement 2 is INSUFFICIENT.

$$Answer\ is\ Option\ A$$