Final answer:
The client demonstrates understanding of taking sublingual nitroglycerin by identifying that the tablet should be placed under the tongue.
Step-by-step explanation:
The correct answer to where a sublingual nitroglycerin tablet should be placed is c. Under my tongue. Sublingual medication administration involves placing the drug under the tongue where it dissolves and is absorbed into the bloodstream through the tissue there. This route allows for the medicine to work quickly, as it does not have to pass through the digestive system first. Teaching a client to take a sublingual medication correctly is important for the efficacy of the drug and for the safety of the patient.