Answer:
B) Mechanical waves tend to have longer wavelengths.
Step-by-step explanation:
As we know the relation between frequency and wavelength is given as

now we know that
speed of electromagnetic waves are

now we have wavelength of violet light given as


now similarly if we will find the wavelength of red light then it is


now if we use the same formula to find the wavelength of sound then it is
wavelength of note A on guitar

wavelength of note C on guitar

so by above all calculations we can see that frequency of electromagnetic waves are much larger than the frequency of mechanical waves due to which wavelength of mechanical waves is larger than the wavelength os electromagnetic waves.