An electron and a proton, both with the same initial velocity $v_0,$ enter a region with a uniform magnetic field $B$ into the page, as shown, with $|{)}_{v}ec(B).$ Each particle undergoes semi$-$circular motion in the field and exits the field some distance d from the entry point. $($The diagram shows the path for one of the two particles.$)$ Which particle, if either, has the largest d$?$

A$)$ Both have the same d$.$

B$)$ Electron has largest d

C$)$ Proton has largest d