Morning glory is the _____________________________

• A. special flared inlet of the shaft spillway of a dam of very small height
• B. special flared inlet of the shaft spillway of a large dam project
• C. a horizontal tunnel constructed in a shaft spillway across the body of a gravity dam to carry surplus reservoir water to the d/s river
• D. a horizontal tunnel constructed in a shaft spillway of an earthen dam through its foundation to carry surplus reservoir water to the d/s river