Answer:
B. 1
Explanation:
The quantum numbers are:
n -> principal, which represents the shell and varies from 1 to 7;
l -> azimuthal, which represents the subshell and varies from 0 to 3;
ml -> magnetic, which represents the orbital and varies from -l to +l passing by 0;
ms -> spin, which represents the spin of the electron, +1/2 or -1/2
Each orbital (ml) can have at least 2 electrons, each one with different ms numbers. So, only 1 electron is possible to have quantum numbers ml = +1 and ms = +1/2 in the valence shell.
