[单选题]
16.22: For the following nuclear reah1c8 wi*ap/eiction, which9qaj ,(edpph 4 one of the following choices correc j(,9qpaed4p htly identifies the
quantity labeled X?
$_{19}^{40}K$ + $e^-$ → X + $_0^0Ve$
A. $_{19}^{40}K$
B. $_{18}^{40}K$
C. $_{18}^{39}Ar$
D. $_{19}^{39}K$
E. $_{18}^{40}Ar$
