Final answer:
The answer to the question is a gratuitous contract, which is an agreement where one party benefits and the other receives no reciprocal advantage.
Step-by-step explanation:
When one party is obligated for the benefit of the other, but receives no advantage in return, this is a gratuitous contract. A gratuitous contract is where one side provides a benefit or service without receiving anything in return, essentially a one-sided obligation. For example, if someone offers to paint a friend's house as a gesture of goodwill and asks for nothing in return, this constitutes a gratuitous contract.