Final answer:
The last formal step listed in the scientific method is B. Proposing a hypothesis, but the process is ongoing as hypotheses are subject to continuous testing and refinement.
Step-by-step explanation:
The last step in the scientific method is B. Proposing a hypothesis. However, it should be noted that the scientific method is a cyclical process and does not strictly end after a hypothesis is proposed, as hypotheses are continually tested, refined, or replaced based on experimental evidence.
In the scientific method, after making observations, a scientist proposes a hypothesis, which is a testable explanation. The next step involves designing and performing controlled experiments to test the hypothesis. If the results of these experiments contradict the hypothesis, scientists will either revise the hypothesis or discard it entirely. Only after repeated testing and validation can a hypothesis contribute to the development of a scientific theory, which represents a broader explanation of phenomena based on a body of evidence.
The process is iterative, and as new evidence emerges, previously accepted hypotheses and theories may be refined or replaced. This emphasizes the self-correcting nature of science, where scientific knowledge evolves over time through continuous testing, observation, and experimentation.