They would know if they see anything like traces of water or anything else that would be nessecary for a living organism to have. They look for these with technology like the hubble telescope as well as the drone on Mars to gather as much information as possible.
Answer:
A. ingest other fish that are poisonous to humans.
Explanation:
In a food chain a primary consumers eats the producer, a secondary consumer eats the primary consumer and then the tertiary consumer eats the secondary consumer. The level of poison will increase as it goes down the food chain so the tertiary consumer will have the highest amount of toxins in it.
Please continue the question. Or is that it?
I believe it’s the lithosphere
<span>After
digestion, an amino acid not absorbed by the body and not used to build
proteins will first be subjected to removal from its amino group. If they are
not used for protein synthesis, amino acids becomes part of the metabolism
process. The body has the capability to create a subset of amino acids, also
known as non-essential amino acids because we don’t have requirement for them
in our diet. </span>
