A source is radiating power equally in all directions. If source power is P, the power density at distance d is

• A. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/508-292-1.png">
• B. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/508-292-2.png">
• C. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/508-292-3.png">
• D. <img src="/_files/images/electronics-and-communication-engineering/communication-systems/508-292-4.png">