Final answer:
Phenylephrine is the adrenergic agonist commonly present in OTC nasal sprays for nasal congestion relief. Hence the correct answer is option C
Step-by-step explanation:
The adrenergic agonist commonly present in nasal sprays available over-the-counter (OTC) to treat nasal congestion is Phenylephrine. Phenylephrine is an α₁-adrenergic agonist that stimulates adrenergic receptors in the bronchioles of the lungs, causing them to dilate and clearing out mucus from the lower respiratory tract. It is often found in combination with other pharmaceuticals in OTC drugs for congestion relief.
Hence the correct answer is option C