JEE Main Physics question

Two bodies having the same mass 40 kg are moving in opposite directions, one with a velocity of 10 m/s and the other with 7 m/s. If they collide and move as one body, the velocity of the combination is

• (A)10 m/s
• (B)7 m/s
• (C)3 m/s
• (D)1.5 m/sCorrect