A hemispherical tank of radius (R) containing liquid upto height (H1) has an orifice of cross-sectional area (a) at its bottom. The time required to lower the level of liquid from (H1) to (H2) will be

• A. <img src="/_files/images/mechanical-engineering/hydraulics-and-fluid-mechanics/162-166-1.png">
• B. <img src="/_files/images/mechanical-engineering/hydraulics-and-fluid-mechanics/162-166-2.png">
• C. <img src="/_files/images/mechanical-engineering/hydraulics-and-fluid-mechanics/162-166-3.png">
• D. none of the above