In the passage, breakwaters (line 25) means

✂️ a) walls built to keep back water to form a reservoir.

✂️ b) structures built out into the sea to shelter part of a harbor.

✂️ c) floodgates used to let water in or out.

✂️ d) motor-boats able to skim very fast over the surface of water.

✂️ e) dredging machines used for bringing up mud.

Responda: In the passage, breakwaters (line 25) means