Phase 1 clinical trials involve which of the following?

Phase 1 clinical trials are specifically designed to evaluate the safety and tolerability of a drug or treatment in a small group of healthy volunteers. These trials focus on determining how a drug interacts with the human body and identifying any potential side effects. By using healthy individuals, researchers can isolate the effects of the drug without the confounding variables that might be present in patients who already have the disease.

The primary goal during this phase is to understand pharmacokinetics (how the drug is processed in the body) and pharmacodynamics (how the drug affects the body), making this choice the correct answer. It is crucial that these trial participants are free from the disease to provide clear and unbiased results regarding the drug's safety profile.

Other options, such as including patients with the disease or specific populations like minors or the elderly, are more relevant to later phases of clinical trials that focus on efficacy and therapeutic effects rather than initial safety assessments.