Which term describes the ability of a receiver to detect the presence of a signal?

Sensitivity is the measure of a radio receiver's ability to pick up very weak signals. A highly sensitive receiver can detect a faint transmission even when there is background noise, making it crucial for distant or low-power communications. It is easy to confuse sensitivity with other receiver characteristics. While sensitivity is about detecting a signal's presence, 'selectivity' refers to the ability to focus on one specific signal while ignoring others on nearby frequencies. Options like 'Linearity' and 'Total Harmonic Distortion' deal with the purity and quality of the audio or signal reproduction, not the receiver's threshold for detecting an incoming RF signal.