How frequently must an analog signal be sampled to be accurately reproduced?
At least half the rate of the highest frequency component of the signal
At least twice the rate of the highest frequency component of the signal✓Bonne réponse
At the same rate as the highest frequency component of the signal
At four times the rate of the highest frequency component of the signal
Explication
The Nyquist sampling theorem sets the requirement: the sample rate must be more than twice the highest frequency component present. Sampling more slowly folds those components down as false lower-frequency signals, which is aliasing.