Answer: disclose the material fact about the flood hazard to the buyer.
Step-by-step explanation:
Based on the information given in the question, Agent Thurmond must disclose the material fact about the flood hazard to the buyer.
It is advisable and ethical for Agent Thurmond to tell the buyer about the issue with regards to the flooding. This is appropriate in order to avert any controversy or case that may eventually result in the future when the buyer becomes aware of the flood hazard.