The velocity factor for precision metallic gears cut with high accuracy and operating at velocities upto 20 m/s is equal to

• A. <img src="/_files/images/mechanical-engineering/machine-design/601-536-1.png">
• B. <img src="/_files/images/mechanical-engineering/machine-design/601-536-2.png">
• C. <img src="/_files/images/mechanical-engineering/machine-design/601-536-3.png">
• D. <img src="/_files/images/mechanical-engineering/machine-design/601-536-4.png">