What happens to the frequency when the wavelength increases

When the wavelength increases then the frequency decrease more wave crests passed at the fixed point per second. Inversely the same will be repeated vice versa.

Explanation:

The frequency of a wave is defined as the number of waves that pass a particular point. If a wave is oscillating at a high speed,  it is said to have a high frequency. More the number of waves passing  a point, the more the frequency.

The wavelength can be defined as the distance between two consecutive crests and troughs.  Wavelength is also a significant characteristic of a wave.  When the wavelength increases, the frequency decreases. Therefore, they are inversely  proportional.

i think it's c