If p is total internal pressure, d is diameter of pressure conduit and t is thickness of conduit, the Hoop's stress is

• A. <img src="/_files/images/civil-engineering/water-supply-engineering/210-10.108-1.png">
• B. <img src="/_files/images/civil-engineering/water-supply-engineering/210-10.108-2.png">
• C. <img src="/_files/images/civil-engineering/water-supply-engineering/210-10.108-3.png">
• D. <img src="/_files/images/civil-engineering/water-supply-engineering/210-10.108-4.png">