The waves in order from lowest  to highest pitch ​: picture 1,2,3,4
Further explanation
Wavelength : from the crest to the crest of the next wave or the trough to the trough
Frequency (f): number of waves in one second
Can be formulated :
[tex]\tt v=\lambda\times f\\\\f=\dfrac{v}{\lambda}[/tex]
So the frequency is inversely proportional to the wavelength
The smaller the wavelength the greater the frequency and the greater the pitch
From the picture above (transverse wave), we determine the wavelength that is formed:  ⇒1 wavelength =one crest (peak) + trough (base)
wavelength = distance : wave(distance = 4)
[tex]\tt 1\rightarrow 1\dfrac{1}{2}~wave\rightarrow \lambda=\dfrac{4}{1\frac{1}{2} }=2.67 \\\\2\rightarrow 2~wave\rightarrow \lambda=\dfrac{4}{2}=2 \\\\3\rightarrow 2\dfrac{1}{2}~wave\rightarrow \lambda=\dfrac{4}{2\frac{1}{2} }=1.6\\\\4\rightarrow 3~wave\rightarrow \lambda=\dfrac{4}{3}=1.33[/tex]
So picture 1 has the largest wavelength, so it has the smallest frequency and the smallest pitch
