$A$ bullet of mass $m$ moving with velocity $v$ strikes a block of mass $M$ at rest and gets embedded into it. The kinetic energy of the composite block will be

• A
  $\frac{1}{2}mv^2 \times \frac{m}{m+M}$
• B
  $\frac{1}{2}mv^2 \times \frac{M}{m+M}$
• C
  $\frac{1}{2}mv^2 \times \frac{M+m}{M}$
• D
  $\frac{1}{2}Mv^2 \times \frac{m}{m+M}$