Final answer:
Adult stem cells are less pluripotent than embryonic stem cells; they are multipotent and can differentiate only into cell types of their specific tissues, whereas embryonic stem cells are pluripotent and can form any human tissue. Therefore, the correct option is A.
Step-by-step explanation:
A key difference in the potency of adult stem cells compared to embryonic stem cells is that adult stem cells are less pluripotent than embryonic stem cells. Adult stem cells are classified as multipotent, which means they are limited in their differentiation to the types of cells found within specific tissues or organs. In contrast, embryonic stem cells are pluripotent, giving them the potential to differentiate into any type of human tissue, although they cannot support the full development of an organism.