To create a simulation of 20,000 sheep grazing in an isolated valley, a scientist needs to determine the average amount of grass eaten per day by an actual sheep. Which of the following is the best course of action for establishing this parameter?
A. Divide the total amount of grass eaten by all sheep in the valley by 20,000.
B. Determine the average daily grass consumption for 20 randomly selected sheep.
C. Choose a random value to use as the daily amount of grass eaten by one sheep.
D. Measure the amount of grass eaten per day by a single sheep.