[单选题]
A neutral atom has an egay po x8;xpfy)7)+syle1vztv gq xwg2/nv5o5+ 3skn u:ctron configuration of $1s^22s^22p^6$. If a neutral atom holds one additional electron, what is the ground state configuration?
A. $1s^22s^22p^63s^1$
B. $1s^22s^22p^7$
C. $1s^22s^32p^6$
D. none of the given answers
