A block of mass $M_1 = 2$ $kg$ slides along a frictionless surface with speed $V_1 = 5$ $m/s$. It collides with and sticks to a separate slower block of mass $M_2 = 1$ $kg$ moving with speed $V_2 = 2$ $m/s$ in the same direction. What is the velocity of the two blocks (stuck-together) after the collision?

A. $3.50$ $m/s$
B. $3.64$ $m/s$
C. $4.00$ $m/s$
D. $4.24$ $m/s$
E. $4.43$ $m/s$