Property of Low Pass filter in Communication

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Assertion: LPF are used to eliminate the higher (greater than 3rd)side lobes of an energy signal whose Fourier Transform spans an infinite duration 

Reason:For a finite duration signal, the Fourier transform of the energy is concentrated in it's main lobe (upto 95%) & upto 99% till it's 3rd lobe, the remaining higher order side lobes are insignificant

(a) Both the first and second statements are true 
(b) Both the first and second statements are true and the second is the correct reason of the first
(c) either of them are true
(d) both are false

Answer is (b)

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