A hemispherical tank of radius (R) has an orifice of cross-sectional area (a) at its bottom and is full of liquid. The time required to empty the tank completely is

• A. <img src="/_files/images/mechanical-engineering/hydraulics-and-fluid-mechanics/163-167-1.png">
• B. <img src="/_files/images/mechanical-engineering/hydraulics-and-fluid-mechanics/163-167-2.png">
• C. <img src="/_files/images/mechanical-engineering/hydraulics-and-fluid-mechanics/163-167-3.png">
• D. <img src="/_files/images/mechanical-engineering/hydraulics-and-fluid-mechanics/163-167-4.png">