A) it represents trough fill rate. It basically states after 8 minutes, the water level raised 28 cm.
B) for every 1 minute of pouring, the water level rises 3.5 centimeters.
C) if you look at those points as proportions
6/21 = 1/3.5
Or 8/28 = 1/3.5
They both can be proportionate.
