Final answer:
The least likely outcome for a real estate professional who knowingly misled a buyer is a successful defense based on loyalty to the seller, as this does not justify misleading the buyer. The professional is more likely to face intentional misrepresentation charges, license revocation, or a lawsuit for damages.
Step-by-step explanation:
The question revolves around potential consequences for a real estate professional who misled a buyer about the condition of a home's foundation. Among the listed outcomes, successful defense against all charges based on loyalty to his client-seller is the least likely. Loyalty to a seller does not permit a real estate agent to deceive a buyer. Any intentional misrepresentation about the property can lead to the real estate professional being charged with intentional misrepresentation. Furthermore, because the real estate professional failed to disclose a material fact, which is a serious violation, he could face the revocation of his license. As for the buyer, they would have a strong case for a suit to recover money damages due to the misrepresented foundation leading to basement leakage and other potential issues arising from the sinking foundation.