Final answer:
The last step in a proof is the conclusion, which is the final statement that demonstrates the truth of the proposition. In contrast, a hypothesis is a tentative explanation that can be closest associated with the notion of a suggestion.
Step-by-step explanation:
The last step in a proof contains the conclusion. A proof is a series of statements in mathematics that demonstrates the truth of a theorem or proposition. Starting with the given information, you use logical reasoning to arrive at a conclusion that's supported by evidence presented throughout the proof. If we look at the choices provided in the question, we find that an assumption is something that is accepted as true without proof, which typically forms the basis of a proof, but is not its concluding statement. A proof statement is another term for a step or argument within the proof, and a hypothesis is a supposition or proposed explanation that leads into a proof but again is not the end result. Therefore, the last step in a proof is the conclusion.