Explanation: I think camouflage method or a design that scares away predators.
Answer:
Vestigial organs are a type of homologous organs.
Explanation:
Vestigial organs are rudimentary in present organisms. Vestigial organs such as wisdom teeth,nictating membrane of eyes,body hairs,which were functional organs in ancestors. Though they are present in an organism in reduced form but are functionless.
Examples of vestigial organs:
1. Human tail or appendix,
2. Pelvic bone of a snake
3. Wings of flightless birds
4.Male breast tissues and nipples
<span>Unidirectional flow in the heart is ensured because the heart contains valves that prevent backflow.
These valves keep the flow of the heart going in one direction (hence the name "unidirectional").</span>
1 is the answer because it’s talking about chemical