Correct option is : (c) r1 : r2
Since the time periods of cars are same, therefore their angular velocities will also be same.
∵ Centripetal acceleration a = rω2
\(\therefore\ \frac{a_1}{a_2} = \frac{r_1\omega^2}{r_2\omega^2} = \frac{r_1}{r_2\ }\ or\ \frac{a_1}{a_2} = \frac{r_1}{r_2}\)
∴ Option (c) is correct.