Answer
See answers.
Work Step by Step
See the Feynman diagram for the reaction. The neutron is on the lower left, and the proton is on the upper left.
A muon neutrino and a muon, which are leptons, are part of the interaction. Therefore, the reaction is a weak interaction, mediated by either W or Z particles.
The lepton changes sign, so a W boson must be involved (because Z particles are not charged).
We draw the diagram by assuming that the neutron emitted a $W^-$ boson that interacted with the neutrino.
