Final answer:
c. Spread Spectrum. Spread Spectrum technology is used in wireless communications to secure signals from interception by spreading them across a wide range of frequencies.
Step-by-step explanation:
The technology that can be applied to wireless communications making them virtually impervious to interception is c. Spread Spectrum. Spread Spectrum technology involves spreading the transmitted signal across a wide range of frequencies which makes it harder to intercept or jam.
This is different from pulse code modulation or frequency modulation, which are other methods of signal modulation but do not inherently provide the same level of security against eavesdropping or interference.
The technology that can be applied to wireless communications, making them virtually impervious to interception is Spread Spectrum (c). Spread Spectrum is a method that spreads the signal over a wide range of frequencies, making it more resistant to interference and interception. It achieves this by using a wider bandwidth than the actual information signal.