Which of the following activities would EXCLUDE an animal from USDA category B?

The correct answer is based on the definitions outlined by the USDA regarding animal categories. USDA category B specifically includes animals that are used in research or teaching but have not been subjected to any experimental manipulation.

Blood collection is a procedure that involves direct intervention with the animal, impacting its physical state and potentially causing pain or distress. This falls outside the criteria for category B animals, which typically encompasses activities that do not involve interventions.

In contrast, the other activities listed—observation without intervention, feeding trials, and behavior assessments—do not require any physical interaction that alters the animal's condition or well-being. Therefore, they would qualify animals to remain within USDA category B, as they represent non-invasive observations and assessments. These activities can provide valuable data while minimizing stress or harm to the animals involved.