Which is one of the four stages of digestion?

• A. Ingestion
• B. Respiration
• C. Fermentation
• D. Germination

Answer: (A)

The main idea here is the sequence of processing food in the digestive system. Ingestion is the first stage, where food is taken into the mouth and begins to be prepared for digestion—chewing breaks it up and saliva starts chemical breakdown, setting the material up for the later stages of digestion, absorption, and elimination. The other options aren’t part of digestion: respiration is about exchanging gases for cellular energy, fermentation is a microbe- or cell-level process that breaks down sugars without oxygen (not a stage of digestive processing in humans), and germination is seed sprouting. So ingestion is the correct choice because it marks the entry and initial processing of food in the digestive system.