[单选题]
A neutral atom has an electrcajpgz ;*.c ;hdugvvk c v+ u/yd-:2pam4t v/+on 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
