Answer:
They do not cause phase-distortion of an input signal. ( option 2 )
Explanation:
Linear-phase filters are desirable in many applications simply because they do not cause phase-distortion of an input signal.
The signals inputted into a Linear-phase filter ( FIR type ) are delayed equally as frequency is delayed in the pass band but they are are distorted.
The main special function of the Linear-phase filter is to reduce signal distortion.
