Answer
a) is correct.
Work Step by Step
The wheels of the bicycle are carrying out rolling motion, which means the distance traveled by the bicycle equals the arc length made by the bicycle's wheel: $$d=s_{arc}=r\theta$$
Here, we are given the distance the bike travels $d=3km=3\times10^3m$ and the wheel's radius $r=0.4m$
The wheel's displacement, therefore, is $$\theta=\frac{d}{r}=7.5\times10^3rad\times\Big(\frac{1rev}{2\pi rad}\Big)\approx1.2\times10^3 rev$$
a) is correct.
