Consider the following definite integral: $I= \displaystyle{} \int_0^1 \dfrac{(\sin ^{-1}x)^2}{\sqrt{1-x^2}} dx$. The value of the integral is

1. $\dfrac{\pi ^3}{24} \\$
2. $\dfrac{\pi ^3}{12} \\$
3. $\dfrac{\pi ^3}{48} \\$
4. $\dfrac{\pi ^3}{64}$