In which pair do both atoms have one electron only in an s orbital in their ground states?

A Ca, Sc B Cu, Be C H, He D Li, Cr

what does electron in GROUND STATES means?
and what is the possible answer?

Question

In which pair do both atoms have one electron only in an s orbital in their ground states?

A    Ca, Sc                B    Cu, Be                C    H, He                  D    Li, Cr

what does electron in GROUND STATES means? 
and what is the possible answer?

anonymous · Answer

chromium has electronic configuration of 1s2 2s2 2p6 3s2 3p6 3d5  4s1 and Li being the group one metal has one electron in its outermost electron. D

anonymous · Answer

what does basically ground states mean?

anonymous · Answer

stable state means the stable state