X is a non-negative integer valued random variable with\( P(X = x) =\left\{ \begin{matrix} \dfrac {x+1}{2^{(x+2)}} & x = 0, 1, 2... \\\ 0 & \rm{otherwise} \end{matrix} \right.\)Then, mean and variance of X are respectively

• A. 2 & 2
• B. 2 & 3
• C. 4 & 2
• D. 2 & 4