$A$ bullet of mass $m$ travelling at speed $v$ strikes a block of mass $M$ at rest and gets embedded in it. Finally,both will have a combined kinetic energy of:

• A
  $\frac{1}{2}mv^2 \times \left( \frac{m}{m + M} \right)$
• B
  $\frac{1}{2}mv^2 \times \left( \frac{M}{m + M} \right)$
• C
  $\frac{1}{2}mv^2 \times \left( \frac{M + m}{M} \right)$
• D
  $\frac{1}{2}mv^2 \times \left( \frac{M + m}{m} \right)$