Answer:
B
Step-by-step explanation:
This looks like a momentum question. It also looks like there is no horizontal acceleration.
Momentum before Momentum after
m1vo (m1 + m2)*vo/3 multiply through by 3
3 m1*vo m1* vo + m2*vo subtract m1*vo from both sides
3m1*vo - m1*vo m2*vo
2m1*vo m2*vo Divide by vo
2m1 = m2
Conclusion: It takes 2 m1's to equal 1 m2.
B is the answer.