Emile wants to earn $100. She picks blueberries and is paid x dollars a bucket. She averages 4 buckets per day, and she has already picked blueberries for 5 days.
Which of the following expression represents how much more money she needs to earn to meet her goal?
A. 20x
B. 80x
C. 20(5 - x)
D. 20(5d-1)