In a single-tone FM discriminator (S0/N0) is

1. proportional to deviation
2. proportional to cube of deviation
3. inversely proportional to deviation
4. proportional to square of deviation

SNR in single tone FM is given by

	δ₀		=	3	β²
	N₀			2

	δ₀		=	3		Δf		²
	N₀			2		f_m

	δ₀			∝ Δf²
	N₀

i.e. square of frequency deviation