The accurate representation of the distinguishing features of the terms is:
- A postulate is assumed to be true, and it does not have to be proven.
The other statements are incorrect or misleading:
- A definition is a statement that explains the meaning of a term, not based on observations or needing proof.
- A theorem is a statement that has been proven to be true based on previously established statements, such as postulates or other theorems.
- A conjecture is an unproven statement or hypothesis based on observations, not a definition.
So, the correct identification is: A postulate is assumed to be true, and it does not have to be proven.