Answer:
SURGERY.
Step-by-step explanation:
Based on classification by the United States department of Agriculture, Category C, animals are exempted from procedure that can inflict pain, or distress.in addition any procedure that involved the use of analgesics (e.g. surgery) should not be performed on the animals.
Besides, regular procedures, of administration of injections and taken blood samples(preparation for surgery) which may produce minimal discomfort are also classified in this category.