Which of the Following Reactions Is an Example of Positron ${ }_{91}^{227} \mathrm{~Pa} \rightarrow{ }_{89}^{223} \mathrm{Ac}+{ }_{2}^{4} \mathrm{He}$

Which of the following reactions is an example of positron emission?

A) ${ }_{91}^{227} \mathrm{~Pa} \rightarrow{ }_{89}^{223} \mathrm{Ac}+{ }_{2}^{4} \mathrm{He}$
B) ${ }_{20}^{41} \mathrm{Ca}+{ }_{-1}^{0} e \rightarrow{ }_{19}^{41} \mathrm{~K}$
C) ${ }_{79}^{201} \mathrm{Au} \rightarrow{ }_{80}^{201} \mathrm{Hg}+{ }_{-1}^{0} \mathrm{\beta}$
D) ${ }_{63}^{150} \mathrm{Eu} \rightarrow{ }_{62}^{150} \mathrm{Sm}+{ }_{+1}^{0} \beta$
E) ${ }_{26}^{58} \mathrm{Fe}+{ }_{0}^{1} n \rightarrow{ }_{26}^{59} \mathrm{Fe}$