What structure is designed to protect harbor entrances by deflecting waves, usually built in pairs?

• A. Seawalls
• B. Breakwater
• C. Jetties
• D. Groins

Answer: (C)

Jetties extend from the shoreline into the sea on opposite sides of a harbor entrance. Their main job is to deflect incoming waves away from the mouth, which reduces wave energy inside the channel and helps keep the entrance open for ships. Building them in pairs creates a sheltered, navigable passage between the structures, making it easier for vessels to enter and exit. They can also influence sediment flow around the harbor, sometimes altering where sand accumulates. Other structures serve different purposes: seawalls protect the land along the shore, breakwaters create a protected area but aren’t specifically built in pairs at harbor entrances, and groins trap sediment along the coastline rather than shield a harbor mouth.