What are the three phases of clinical trials?

The correct choice identifies the three primary phases of clinical trials that are critical in the evaluation of a new drug or treatment's safety and efficacy. In Phase I, the focus is on assessing the safety, tolerability, pharmacokinetics, and pharmacodynamics of a drug in a small group of healthy volunteers. This phase helps determine the appropriate dosage and identifies any potential side effects.

Phase II trials involve a larger group of participants and are primarily concerned with evaluating the treatment’s effectiveness and further assessing its safety. This phase helps confirm the early findings from Phase I regarding safety and starts to provide data on how well the new drug works.

Phase III trials are conducted on an even larger scale and are designed to confirm effectiveness, monitor side effects, and compare the new treatment to standard or equivalent treatments. The data obtained from Phase III trials are often the basis for regulatory approval for the drug, as they provide comprehensive information on the drug’s effectiveness and the risks involved.

After these three phases, additional studies might be conducted in Phase IV, which is post-marketing surveillance to track the drug's performance in the general population and to monitor for any long-term side effects.

The other options fail to correctly define the standard phases of clinical trials, either omitting a