How do decongestants function in animals?

Decongestants work primarily by reducing inflammation and relieving congestion in the respiratory tract. In both animals and humans, these medications target blood vessels in the nasal passages, causing them to constrict. This vasoconstriction reduces swelling and inflammation in the nasal tissues, allowing for clearer airways and easier breathing. The active components in decongestants often include substances that can shrink mucous membranes, leading to decreased production of mucous and alleviating symptoms associated with congestion such as nasal obstruction.

The other options do not align with how decongestants function. Stimulating appetite, increasing heart rate, and acting as a sedative pertain to different classes of drugs or physiological responses that are not a primary action of decongestants. By focusing on inflammation reduction and congestion relief, decongestants provide targeted therapeutic benefits, making option B the correct choice.