From an Ethical Point of View, What Is the Point

From an ethical point of view, what is the point of determining that a potential research participant is incompetent?

A) An incompetent participant must receive more extensive explanation before consenting to participate in research.b.According to HIPAA, a different level of records security must ensue.
C) Inclusion of the participant necessitates a different consenting process.
D) The researcher has a responsibility to exclude all incompetent persons from research participation.