Explanation: Noise figure measures how much a receiver degrades the signal-to-noise ratio (SNR) by adding its own internal noise. It quantifies the excess noise generated within the receiver's front-end and subsequent stages, beyond the inherent thermal noise present at the input. A lower noise figure indicates better performance for weak signals, as the receiver contributes less unwanted internal noise. Therefore, option C accurately describes the level of noise generated internally by the receiver. Option A refers to external noise entering from the antenna, not the receiver's internal contribution. Option B describes aspects of selectivity or filter characteristics, unrelated to noise figure. Option D describes receiver selectivity, which is its ability to reject adjacent interfering signals, distinct from its internal noise performance.