The Lowest Notch Shown on This Figure Is 9 Meters

Multiple Choice

The lowest notch shown on this figure is 9 meters wide and 5 meters high from its base.The river has a velocity of 1 meter per second when it fills the notch.Based on the accompanying graph,what is the probability each year that the notch will be filled to the top?

A) 90% to 95%
B) 60% to 80%
C) 40% to 45%
D) Less than 40%
E) None of these are correct.