Which of the following best describes what alveolar are

Alveoli are tiny balloon shaped structures and are the smallest passageway in the respiratory system. The alveoli are only one cell thick, allowing the relatively easy passage of oxygen and carbon dioxide (CO2) between the alveoli and blood vessels called capillaries.

The charge of an ion with 55 protons and 52 electrons is +3. the reason is because protons are positive, and there are three more than the amount of negative electrons.

Are there options for this?