Correct Option: C

GivenT.F. =	G(s)
	1 + G(s) H(s)

=	an-1 s+an
	sn + a1sn-1 + ........+an-1s+an

or

G(s)	=	an-1 s+an
1 + G(s)		sn + a1sn-1 + ........+an-1s+an

[∴ H(s) = 1]
[1 + G(s)_{an – 1} s + a_n] = G(s) [sⁿ + a₁ s^n–1 + a₂ s^{n – 2} … + a_{n– 1} s + a_n]
or
a_n = G(s) [sⁿ + a₁s^n–1 + a₂ s^n–2 + … + a_n–2s²]
or

G(s) =	an
	[sn + a1 sn–1 + a2 sn–2 + … + an–2 s2]

Now,

ess = s → 0Lim	R(s)
	1 + G(s)H(s)

= s → 0Lim	1/s2
	1 + [sn + a1sn-1 + a2sn-2 + ......+an-2s2].1

[If r(t) = tu(t) then R(s) = 1/s²]

= s → 0Lim	sn+a1sn-1+a2sn-2+........+an-2s2
	s2 [sn + a1sn-1 + a2sn-2 + ......+an-2s2an]

= a_n–2/a_n
Hence alternative (C) is the correct choice.