Final answer:
An acid solution contains more hydronium ions than hydroxide ions, due to the excess protons present in the form of hydronium ions. Therefore, the correct answer is b) Protons, electrons.
Step-by-step explanation:
An acid solution contains more hydronium ions (H3O+) than hydroxide ions (OH-). When an acid dissolves in water, it donates protons (hydrogen ions, H+) to water molecules, forming hydronium ions. The correct answer to the student's question is b) Protons, electrons, since the presence of excess protons in the form of hydronium ions relative to electrons is characteristic of an acidic solution.
As an example, a sodium cation (Na+), which is formed by a loss of an electron from a sodium atom, ends up with more protons than electrons, resulting in a positive charge. Similarly, in an acid solution, there are more hydronium ions with positive charge than there are negatively charged particles, indicating an excess of protons.