A. Areas within an energy level that are occupied by electrons
There are different energy levels where electrons (probably) are, they are hanging out in the orbitals, or energy levels around the nucleus.
We know the other options are wrong because protons are in the nucleus of an atom, neutrons have a neutral charge, and although B sounds right, A is the more accurate choice
The answer is each indicator has a narrow range. We need many different indicators to span the entire ph spectrum because each indicator has a narrow range.
