An oil tank is being drained for cleaning. After t minutes there are Vlitres of oil left in the tank, where vo) = 10(10-1', 0S $10. Determine the rate of change of volume at the time t = 5 minutes. ( a) -100 litres/min. Ob) -200 litres/min. O c) _so litres/min. O d) -150 litres/min