If wavelength in free space is 0 wavelength in insulator , r is relative permittivity or insulator and r is relative permittivity or insulator, then

• A. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/11-72-1.png">
• B. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/11-72-2.png">
• C. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/11-72-3.png">
• D. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/11-72-4.png">