##Explanation: 1.1
  *
  |__polluted_river(rhin)
  |  |__river(rhin)
  |  |__entity(a)
  |  |  |__factory(a)
  |  |__entity(b)
  |  |  |__factory(b)
  |  |__entity(c)
  |  |  |__farm(c)
  |  |__chemical(a,rhin,30)
  |  |__chemical(b,rhin,60)
  |  |__chemical(c,rhin,10)
  |  |__nutrient(c,rhin,30)

##Total Explanations:   1