The basic requirement that must be met for an experiment to be morally legitimate is that

A) the experiment must be beneficial to the subject.
B) the experiment must be beneficial to mankind.
C) the subject must have given informed consent to be involved.
D) the experiment must be legally permissible.

Informed consent is the cornerstone of ethical experimentation. It is essential that the subject understands the nature and purpose of the experiment, as well as any potential risks or benefits. Without informed consent, an experiment is not morally legitimate, even if it is beneficial to mankind or legal. It is also important that the subject be free to withdraw from the experiment at any time without penalty or coercion.