For the following probability distribution:

Question

X 1 2 3 4 P(X) $\Large\frac{1}{10}$ $\Large\frac{1}{5}$ $\Large\frac{3}{10}$ $\Large\frac{2}{5}$ $E(X^2)$ is equal to \[(A)\;3\quad(B)\;5\quad(C)\;7\quad(D)\;10\]