Question

Need help with this as well as explanation

Answer 1

i'm a little rusty on quantum theory but here are my thoughts:

factors affecting energy of an electron: distance from the nucleus, and any shielding/penetrating effects

comparing, say, 2s and 2p, the 2p orbital is farther away and thus more shielded from the nucleus on average so the 2p orbital has higher energy

penetration is basically the likelihood/ability of an electron to approach the nucleus. 2s is closer to the nucleus and has a higher penetration effect

so I'd hesitatingly say all three (ABC)