One object of mass 20 kg is moving with speed $10 {\mathrm{ms}}^{-1}$ in west direction and another object of mass 10 kg is moving with $15 {\mathrm{ms}}^{-1}$ in north direction. Both collide and stick together. Choose the correct alternative. [JIPMER 2019]

• A

  Their kinetic energy is conserved as it is inelastic collision.

• B

  Their kinetic energy is conserved as it is elastic collision.

• C

  Their momentum is conserved as it is inelastic collision.

• D

  Their momentum is conserved as it is elastic collision.