In the given diagram, with what force must the man pull the rope to hold the plank in position? Mass of the man is 80 kg. Neglect the weights of plank, rope and pulley. Take g=  l0 ${\mathrm{ms}}^{-2}$.

• A

  200 N

• B

  300 N

• C

  600 N

• D

  150 N