Correct Option: B

Phase cross-over frequency for the given transfer function

G(s)H(s) =	1
	s(s + 1)(s + 0·5)

∠G(s H(s) = – 90° – tan^–1(ω/1) – tan^–1(ω/0.5)
– 180° = – 90° – tan^–1 ω – tan^–1 (2ω)

or 90° = tan–1		ω + 2ω		⎪at ω = ωP
		1 – ω.2ω

or tan 90° =	3ω	⎪at ω = ωP
	1 – 2ω2

or	1	=	3ω	⎪at ω = ωP
	0		1 – 2ω2

or 1 – 2 ω²_P = 0
or ω_P = 1/√2
ω_P = 0.707 rad/sec.