Answer is A
Firstly axon must reach the threshold level and then depolarisation occurs. Depolarisation phrase means sodium enters and potassium leaves the axon . Choice C can't be because main idea is the entering of sodium ions.
I'll say that it is +1 since hydrogen is desperate to lose an electron to fulfill the octave rule (that the molecules want to gain 8 electrons and if they can't do it, they want to lose all their electron). Electron is - so if it lose a electron, it becomes +.
Hopefully this helps.
PS. I'm not certain of my answer but it is logical.
If the tyre blows out then stop
