Correct Option: B

Given equation s(t) = cos 2π (2 × 10⁶t + 30 sin 150t + 40 cos 150t) …(1)
From equation (1)
θ(t) = 2 × 10⁶t + 30 sin 150t + 40 cos 150t
or

dθ(t)	= 2 × 106+ 30.150 cos 150t + 40.150 sin 150t
dt

or

dθ(t)	= 2 × 106 + √ 302 + 402 cos(150t + φ)
dt

or

dθ(t)	= 2 × 106 + 7500 cos (150t + φ)
dt

Where,

φ = tan−1		−	40
			30

We know that,

dθ(t)	= ωi
dt

2 × 10⁶ = ω_c
Frequency deviation
⇒ ω_i − ω_c = 7500 cos (150t + φ)
|ω_i − ω_c|_max = 7500 radian/sec.
Hence alternative (B) is the correct choice.