Correct option is : (b) 2:1
Ratio of accelerations in given situations:
\(\frac{a_1}{a_2} = \frac{\frac{g\sin\theta}{g\sin\theta}}{1 + \frac{K^2}{R^2}} = 1 + \frac{K^2}{R^2}\)
For ring I = MK2 = MR2 \(\Rightarrow\frac{K^2}{R^2} = 1\)
\(\therefore\ \frac{a_1}{a_2} = 1 + 1 = 2\)
\(\therefore\ a_1 : a_2 = 2:1\)
Thus option (b) is correct.