Final answer:
Real Estate Consultants are the professionals who advise on the purchase and use of real estate investments by analyzing market trends and property potential.
Step-by-step explanation:
The professionals who provide advice to individuals and firms regarding the purchase and use of real estate investments are D) Real Estate Consultants. These experts specialize in understanding the market trends, valuation, and the development potential of properties. They assist their clients in making informed decisions about buying, selling, or investing in real estate, ensuring that their investments are sound and potentially lucrative.