Topic: System of Masses
Concepts: Conservation of linear momentum

Solution:

• (a) True in both cases by the conservation of linear momentum. The velocity vectors of the daughter particles must lie in a single line in the two-body case but that is a special case of being in a single plane.
• (b) True in the two-body case but false in the three-body case. We have conservation laws
  
  $K=\frac{1}{2}m_1v_1^2+\frac{1}{2}m_2v_2^2$
  
  $0=m_1v_1+m_2v_2$
  
  for the two-body case which is 2 equations for 2 unknowns. The three-body case has more unknowns than equations.
• (c) False in both cases since the masses are unknown.
• (d) True in both cases by the conservation of linear momentum.
• (e) Not applicable.

Thus, the answer is B.