When a Neutron Decays, a Proton and an Electron Are

Multiple Choice

When a neutron decays, a proton and an electron are observed. When the electrons emitted from a sample of neutrons are observed, they are found to have different kinetic energies. This was accounted for by

A) introducing a different particle, the neutrino.
B) introducing the effect of gravity on the particles.
C) including the kinetic energies of the neutron and proton.
D) modifying the laws of conservation of momentum and energy.
E) taking into account the uncertainties associated with Heisenberg's Uncertainty Principle.