Answer:
A) decreasing frequency.
Step-by-step explanation:
The frequency is the number of occurrences of a repeating event per unit of time.
In the figure attached two examples of waves are shown.
From the table in the question, we know that the wavelength increase as time increase, so the time in which the curve pass through some value becomes more and more separated from the previous, and that is equivalent to decrease in the frequency. In other words, the shorter the wavelength, the higher the frequency (there are more repetitions of the event per unit of time); in this exercise the wavelength is increased, then the frequency decrease.