Answer:A
Step-by-step explanation:
Arsenic is a p-block non-metal in group 15. It is found in the 4th period with electron configuration [Ar] 3d10 4s2 4p3
The outermost electrons are 4s2 4p3. The quantum number that fits an electron in the 4p orbital is option A
Since n=4,l=1, m= -1,0,1 ms=±1/2