Which of the following conditions ensures no signal distortion in an LTI system?

Correct option is A

​$$\text{For an LTI system to transmit a signal without distortion (i.e., without altering the waveform shape):} \\[8pt]\bullet \ \text{The magnitude response should be flat (or constant over the signal band), and} \\[4pt]\bullet \ \text{The phase response should be linear with frequency.} \\[10pt]\text{A linear phase response implies a constant group delay, meaning:} \\[8pt]\bullet \ \text{All frequency components of the signal experience the same time delay.} \\[4pt]\bullet \ \text{The signal is delayed in time but not distorted in shape.}$$​​