Which of the following is not a guided medium?

A. Twisted-pair ट्विस्टेड-पेअर

B. Fiber optic cable फाइबर ऑप्टिक केबल

C. Coaxial Cable कोएक्सिअल केबल

D. Atmosphere एटमॉस्फेयर

Correct Answer is :

D. Atmosphere