The maximum efficiency of a square threaded screw is

• A. <img src="/_files/images/mechanical-engineering/machine-design/586-363-1.png">
• B. <img src="/_files/images/mechanical-engineering/machine-design/586-363-2.png">
• C. <img src="/_files/images/mechanical-engineering/machine-design/586-363-3.png">
• D. <img src="/_files/images/mechanical-engineering/machine-design/586-363-4.png">