The table compares the wavelength of some unknown electromagnetic waves.

comparison of wavelength
electromagnetic wave wavelength
a 10−4 m
b 10−6 m
c 102 m
d 100 m

which electromagnetic wave has the lowest frequency?
wave a
wave b
wave c
wave d

Option C. (102 m)

Electromagnetic Wave having highest wavelength has the lowest frequency.

Explanation:

The relation between wave length and frequency of the electromagnetic  wave is inversely proportional if the wave is moving at a fixed speed. So, the largest wave length of electromagnetic wave found during the comparison is 102 m so it must have the lowest frequency.The mathematical relation is given as : v=fλ; where f stands for frequency, λ for wavelength and v for speed of wave.