Fiber Optic is the most resistant to tapping because Fiber Optic uses a light to transmit the signal. While there are some technologies that will allow to monitor the line passively, it is very difficult to tap into without detection sot this technology would be the MOST resistent to tapping.
The following answers are in correct:
microwave. Is incorrect because microwave transmissions can be intercepted if in the path of the broadcast without detection.
twisted pair. Is incorrect because it is easy to tap into a twisted pair line. coaxial cable. Is incorrect because it is easy to tap into a coaxial cable line.