Final answer:
The principle of beneficence is a proxy-decision making standard in which the guardian makes decisions in the best interest of the individual who is unable to make an autonomous decision.
Step-by-step explanation:
The proxy-decision making standard in which the guardian is directed to make the decision in the best interest of the individual is known as the principle of beneficence. This principle is often used in cases where the individual was never in a position to make an autonomous decision, such as when a child needs medical treatment and their parent is making the decision on their behalf.