Answer
a) is correct.
Work Step by Step
According to Newton's 2nd law of rotational motion, $$\sum\tau=I\alpha$$ $$Fr=Mr^2\alpha$$ $$\alpha=\frac{F}{Mr}$$
The smaller hoop's angular acceleration $$\alpha_s=\frac{F}{MR}$$
The larger hoop's angular acceleration $$\alpha_l=\frac{F}{M2R}=\frac{1}{2}\alpha_s$$
So the smaller hoop's angular acceleration is twice as great as that of the larger hoop. a) is correct.
