Final answer:
Phase I studies generally involve 10 to 100 subjects.
Step-by-step explanation:
In Phase I studies, the number of subjects generally ranges from 10 to 100 (option a).
This phase focuses on evaluating the safety, tolerability, and pharmacokinetics of a new drug in a small number of healthy volunteers or patients.
The National Library of Medicine's clinical trials data indicate that there are ongoing clinical trials with a range of subjects, but the typical number of subjects in Phase I studies falls within the given range.