${ }_{26}^{55} \mathrm{Fe}$ , Which Has an Atomic Mass Of $54.938296 \mathrm{u}$

Multiple Choice

${ }_{26}^{55} \mathrm{Fe}$ , which has an atomic mass of $54.938296 \mathrm{u}$ decays with a half-life of $2.7 \mathrm{y}$ to ${ }_{25}^{55} \mathrm{Mn}$ , which has an atomic mass of $54.938047 \mathrm{u}$ . Does this likely decay by a $\beta^{+}$ process (B) , or must it decay by electron capture $(\mathrm{E}) ?$

A) $\beta^{+}$ process
B) must it decay by electron capture