A weightless rod is acted on by upward parallel forces of 2 N and 4 N at ends A and B respectively. The total length of the rod AB = 3 m. To keep the rod in equilibrium a force of 6 N should act in the following manner:

• A

  Downwards at any point between A and B

• B

  Downwards at the midpoint of AB

• C

  Downwards at a point C such that AC = 1 m

• D

  Downwards at a point D such that BD =  1m