The correct answer is: C. canal escape.
A canal escape is a structure that is used to remove surplus water from an irrigation channel into a natural drain. It is typically a small opening in the side of the canal that is controlled by a gate. When the water level in the canal rises above a certain level, the gate is opened and the water flows out of the canal and into the drain.
A canal fall is a structure that is used to reduce the velocity of water in an irrigation channel. It is typically a series of steps or a chute that the water flows over. The canal fall helps to prevent erosion and damage to the canal.
A canal outlet is a structure that is used to divert water from an irrigation channel into another channel or into a field. It is typically a pipe or a gate that is located at the end of the canal. The canal outlet helps to control the flow of water to the fields.
A canal regulator is a structure that is used to control the flow of water in an irrigation channel. It is typically a gate or a valve that is located at the head of the canal. The canal regulator helps to ensure that the water is distributed evenly to all of the fields.