The maximum efficiency of a screw jack is

• A. <img src="/_files/images/mechanical-engineering/theory-of-machines/486-173-1.png">
• B. <img src="/_files/images/mechanical-engineering/theory-of-machines/486-173-2.png">
• C. <img src="/_files/images/mechanical-engineering/theory-of-machines/486-173-3.png">
• D. <img src="/_files/images/mechanical-engineering/theory-of-machines/486-173-4.png">