Research using animals must demonstrate a(n) . clear benefit to other animals. physical or financial benefit to humansc. absence of discomfort or invasive procedures. clear scientific purpose

Option D.

Research using an animal must demonstrate a CLEAR SCIENTIFIC PURPOSE.

Explanation:

A research is a systematic approach or methodology used to investigate a study or sources to get some fact. Animal research is mainly done for medical research and vertebrates like cats are mostly use.

Research using an animal most demonstrate the clear purpose i.e you state the research problem, state your hypothesi, the methods used and conclusion.

they deliver oxygen to the blood