Explain why the virtual particle in this Feynman diagram must be a weak interaction exchange particle.

A student claims that the \({{\text{K}}^ + }\) is produced in neutron decays according to the reaction \({\text{n}} \to {{\text{K}}^ + } + {{\text{e}}^ - }\). State one reason why this claim is false.

the decay does not conserve strangeness;

and only the weak interaction violates strangeness conservation;

or

a neutrino is produced in this decay;

neutrinos interact only via the weak interaction;

does not conserve baryon/quark/lepton number;