Here it says how many octet electrons are around the phosphorus atom in the following compound. So remember your octet electrons equals your valence electrons plus your shared electrons. And if we take a look here, your valence electron number is based on your group number. Phosphorus is in Group 5A so it has five valence electrons, so 1, 2, 3, 4, 5.

And then the shared electrons are the electrons you gain by forming a chemical bond with another element. So here our shared electrons would be the ones that we're gaining from forming a bond with the hydrogen atoms SO 1, 2, 3, 4, and 5. So here we'd see that phosphorus has 10 total octet electrons.

Here this makes sense because we said that when we're dealing with a non octet number of electrons, it's typically twice the group number of the element. Phosphorus is in Group 5A, and if you multiply that by two we typically can see it go all the way up to 10 valence electrons. So that means option B would be our correct choice.