The valve closure is said to be sudden if

• A. <img src="/_files/images/civil-engineering/hydraulics/162-7.275-1.png">
• B. <img src="/_files/images/civil-engineering/hydraulics/162-7.275-2.png">
• C. <img src="/_files/images/civil-engineering/hydraulics/162-7.275-3.png">
• D. <img src="/_files/images/civil-engineering/hydraulics/162-7.275-4.png">