The power of a Porter governor is equal to

• A. <img src="/_files/images/mechanical-engineering/theory-of-machines/504-362-1.png">
• B. <img src="/_files/images/mechanical-engineering/theory-of-machines/504-362-2.png">
• C. <img src="/_files/images/mechanical-engineering/theory-of-machines/504-362-3.png">
• D. <img src="/_files/images/mechanical-engineering/theory-of-machines/504-362-4.png">