The answer is c) Electrical energy
Answer D; if you spray perfume into a corner, it will eventually diffuse, but initially it has a higher concentration than all other corners of that room.
I would say Na. Oxygen has 2 valence electrons and when reacting with other molecules, the ones with the fullest or emptiest shells will react the least. Both H2 and Na are in the Alkali Metals in the first row, but since H2 has 2 molecules, it would use more oxygen than Ana