Fresh water flows beneath the ground. People had to dig down to reach the water. They made a channel. It was a long hole dug into the earth. The underground water collected in the channel. Then people needed a way to get to this water so they could use it.

What does "channel" mean in this passage?

A. a type of boat.

B. a deep cut in a surface.

C. a small container.

D. a plan for building something.​