Final answer:
Carfentanil is commonly used as a large animal tranquilizer.
Step-by-step explanation:
Carfentanil is commonly used as a large animal tranquilizer. It is a potent synthetic opioid that is about 10,000 times stronger than morphine and is used to sedate large animals such as elephants and rhinoceroses during veterinary procedures. Due to its high potency, it is strictly regulated and should only be used by trained professionals.