Maximum efficiency of a screw jack for the angle of friction , is

• A. <img src="/_files/images/civil-engineering/applied-mechanics/114-5.203-1.png">
• B. <img src="/_files/images/civil-engineering/applied-mechanics/114-5.203-2.png">
• C. <img src="/_files/images/civil-engineering/applied-mechanics/114-5.203-3.png">
• D. <img src="/_files/images/civil-engineering/applied-mechanics/114-5.203-4.png">