Question 6
A birdbath is designed to overflow so that it will be self-cleaning. Water flows in at the rate of $20$ milliliters per minute and drains at the rate of $18$ milliliters per minute. One of these graphs shows the volume of water in the birdbath during the filling time and continuing into the overflow time. Which one is it?
**(A)**
**(B)**
**(C)**
**(D)**
**(E)**
**(A)**
**(B)**
**(C)**
**(D)**
**(E)**