A neutron having mass of $1.67\times {10}^{-27}\mathrm{kg}$ and moving at ${10}^8\mathrm{m}/\mathrm{s}$ collides with a deutron at rest and sticks to it. If the mass of the deutron is $3.34\times {10}^{-27}\mathrm{kg}$  then the speed of the combination is

• A

  $2.56\times {10}^3\mathrm{m}/\mathrm{s}$

• B

  $2.98\times {10}^5\mathrm{m}/\mathrm{s}$

• C

  $3.33\times {10}^7\mathrm{m}/\mathrm{s}$

• D

  $5.01\times {10}^9\mathrm{m}/\mathrm{s}$