Suppose the elements $X$ and $Y$ combine to form two compounds $XY_2$ and $X_3Y_2$. When $0.1$ mole of $XY_2$ weighs $10\ g$ and $0.05$ mole of $X_3Y_2$ weighs $9\ g$, the atomic weights of $X$ and $Y$ are

(a) $40,\ 30$

(b) $60,\ 40$

(c) $20,\ 30$

(d) $30,\ 20$

(a) $40,\ 30$

(b) $60,\ 40$

(c) $20,\ 30$

(d) $30,\ 20$