Which type of smooth muscle occurs in the largest arteries and pulmonary air passages?

Multiunit smooth muscle is the correct type of muscle found in the largest arteries and pulmonary air passages. This type of smooth muscle consists of independently functioning fibers that can contract in response to neural input or hormones. In large arteries, such as the aorta, and in the pulmonary air passages, multiunit smooth muscle allows for fine control over the diameter of the vessels and airways, which is crucial for regulating blood flow and airflow respectively.

This muscle type is characterized by its distinct structure, where each muscle fiber is individually innervated, allowing for more precise and varied responses to stimuli, unlike single-unit smooth muscle, which operates in a more synchronized manner. Multiunit smooth muscle is particularly adaptable, making it ideal for locations where rapid or specific changes in muscle tension are necessary to accommodate changing physiological demands.