The number of liters of water remaining in a tank t minutes after the tank has started to drain is R(t) = 2t^3 - 20t^2 -72t + 820. At what moment is the water draining the fastest?

A) 0 min
B) 2 min
C) 10/3 min
D) 16/3 min
E) It drains at the same rate the whole time