Which of these best describes the correct size order in the respiratory system, starting with the largest?
a. Bronchioles, Alveoli, Bronchi, Trachea
b. Trachea, Bronchi, Bronchioles, Alveoli
c. Alveoli, Bronchioles, Trachea, Bronchi
d. Bronchi, Trachea, Alveoli, Bronchioles