Correct Option: C

m(t) s(t) = y₁(t)
=

=	2 sin (2πt) cos(2πt)
	t

or

y1(t) =	2 sin (2πt) cos(2πt)
	t

...(A)
y₂(t) = y₁(t) + n(t)

=	sin 202πt - sin 198πt	+	sin 198πt
	t		t

...(B)
Now y(t) = y₂(t).s(t)

=	[sin 202πt - sin 198πt + sin 199πt]cos 200πt
	t

or

y(t) =	1	[sin (402πt) + sin(2πt) − {sin(389πt) − sin2πt} + sin(399πt) − sin(πt)]
	2t

...(C)
After filtering equation (C) through LPF with cut-off frequency 1 Hz we get
or

y(t) =	sin (2πt) + sin (2πt) − sin (πt)
	2t

or

y(t) =	sin (2πt) + 2sin (0.5t) cos(1.5πt)
	2t

or

y(t) =	sin (2πt)	+	sin 0.5t	cos 1.5πt
	2t		t

Hence alternative (C) is the correct choice.