Which of the Following Reactions Is an Example of Beta ${ }_{42}^{99} \mathrm{Mo} \rightarrow{ }_{43}^{99} \mathrm{Tc}+{ }_{-1}^{0} e$

Which of the following reactions is an example of beta particle emission?

A) ${ }_{42}^{99} \mathrm{Mo} \rightarrow{ }_{43}^{99} \mathrm{Tc}+{ }_{-1}^{0} e$
B) ${ }_{19}^{40} \mathrm{~K}+{ }_{-1}^{0} e \rightarrow{ }_{18}^{40} \mathrm{Ar}$
C) ${ }_{19}^{40} \mathrm{~K} \rightarrow{ }_{18}^{40} \mathrm{Ar}+{ }_{1}^{0} e$
D) ${ }_{92}^{238} \mathrm{U} \rightarrow{ }_{90}^{234} \mathrm{Th}+{ }_{2}^{4} \mathrm{He}$
E) ${ }_{90}^{232} \mathrm{Th} \rightarrow{ }_{88}^{228} \mathrm{Ra}+{ }_{2}^{4} \mathrm{He}$