Efficiency of a screw jack is given by(where = Helix angle, and = Angle of friction.)

• A. <img src="/_files/images/mechanical-engineering/engineering-mechanics/34-130-1.png">
• B. <img src="/_files/images/mechanical-engineering/engineering-mechanics/34-130-2.png">
• C. <img src="/_files/images/mechanical-engineering/engineering-mechanics/34-130-3.png">
• D. <img src="/_files/images/mechanical-engineering/engineering-mechanics/34-130-4.png">