What is the number of waves that pass a fixed ping in a given amount of time?

The number of waves that pass a fixed point in a given amount of time is wave frequency. Wave frequency can be measured by counting the number of crests (high points) of waves that pass the fixed point in 1 second or some other time period. The higher the number is, the greater the frequency of the waves. :)

Golf is for old men who smell

If its history of, then b) because a) implies only present day (now)