Question

A strong structure that enables us to cross the river is
a) road
b) bridge
c) canal

Answer 1

bridge is the answer

Answer 2

b) bridge

Why the other ones are wrong:

a) To build a road, you need another support or ground to build it. You can't build a road on just water without a bridge.

c) A canal is an artificial waterway made by humans to navigate when water transportation is used. Canals are basically bridges for boats to cross the land instead of how bridges are used to cross rivers to the land.