Which set correctly lists the four routes of entry into the body?

• A. Inhalation, ingestion, excretion, absorption
• B. Inhalation, digestion, injection, absorption
• C. Inhalation, ingestion, injection, absorption
• D. Inhalation, ingestion, injection, excretion

Answer: (C)

Substances can enter the body through four principal routes: inhalation through the lungs, ingestion via the mouth into the digestive system, injection through puncture or needle, and absorption across skin or mucous membranes. This set aligns with those pathways, so it’s the best choice. Excretion is the body's way of eliminating waste and not a route for entry, and digestion refers to processing food in the digestive system rather than how a substance gets absorbed into the body. So inhalation, ingestion, injection, and absorption correctly enumerate the four routes of entry.