Which of the following is an example of a man-made site?

• A. Coral reef
• B. Submerged cavern
• C. Seagrass meadow
• D. Breakwater

Answer: (D)

Understanding what counts as a man-made site helps distinguish human-made structures from natural underwater features. A breakwater is a structure built by people, typically to protect coastlines or harbors from waves, and it becomes an artificial feature in the marine environment. The other options—coral reef, submerged cavern, and seagrass meadow—are all natural formations formed without human construction. So the breakwater is the example of a man-made site.