The basic relationship between the frequency of a wave and its period is

where f is the frequency and T the period of vibration.
In our problem, the frequency is

so, by re-arranging the previous formula, we can find the period of the wave:
I think the answer is B but not too sure.
False, the smaller the load a river has the more sediment it can carry
The number of back-and-forth vibrations in a unit of time is an object's frequency. A complete back-and-forth vibration is one cycle. 1 Hz is one vibration or wave cycle per second!