A 10-year-old boy oversleeps and is late for

school in the morning. It is cold outside and he runs away to avoid being late.

Unfortunately, he is asthmatic and the combination of cold air, physical

exertion, and fear of being late causes him to have an asthma attack. He has

trouble breathing, feels chest tightness and a feeling of lack of air. A low

whistling sound is heard during his exhalation. The boy carries an inhaler

which he uses and manages to control the attack. During an asthma attack, there

is swelling of the mucous membranes, excessive secretion of the bronchial

glands, and contraction of the smooth muscles. It also affects the small

bronchioles, the wall of which is not strengthened by cartilage. Which picture

shows a picture of such a bronchiole?