Final answer:
An anti-aliasing filter is used to remove high-frequency components from a continuous analog signal before it is sampled and digitized, which helps to prevent aliasing and maintain the integrity of the original signal.
Step-by-step explanation:
When a continuous signal is passed through an anti-aliasing filter, the result is option 3) The signal is filtered to remove high-frequency components. An anti-aliasing filter is a low-pass filter that is used before the analog-to-digital conversion process. Its primary function is to limit the bandwidth of a continuous, analog signal to satisfy the Nyquist criterion, which states that the sampling rate must be at least twice the highest frequency present in the signal to avoid aliasing. Aliasing is a form of distortion that occurs when higher frequencies are incorrectly represented as lower frequencies in the sampled signal.
Anti-aliasing filters do not amplify the signal (option 1) nor do they attenuate the signal in a general sense (option 2), although they might attenuate frequencies beyond the cutoff frequency. They certainly do not convert the signal to a digital signal (option 4); that is the job of an analog-to-digital converter (ADC). Therefore, an anti-aliasing filter's role is crucial in preserving the integrity of the original analog signal by eliminating frequencies that could cause aliasing before it is sampled and converted to digital form for electronic processing.