"Which of the following CANNOT be the group of employees assigned to the retailers booth."
All of these answer choices have 3 employees at the retail booth. That means that we are dealing with two possible formats:
O _ _ R _ _ _ V _
or
O _ R _ _ _ V _ _
Pay extra close attention to the GM block, and note that they cannot go to the organizer booth. G, H, and M all cannot be at the organizer booth. F and K cannot be at the visitor booth.
A. R: F G M This forces K into the organizers booth, but that should work for either diagram. No problems here.
B. R: F H K We now have to place the GM block at the visitors group. This leaves L for the organizers booth. We're using the second diagram, but no problems here.
C. R: F H L Again, GM has to go to the visitors booth. K must go to the organizers booth. No problems here.
D. R: F K L GM is sent to the visitors booth. Who is left? Only H. There is nowhere for H to go. He is blocked from the organizers booth. This is our correct answer.
E. R: G L M F and K have to go to the organizers booth. This leaves H for the visitors booth. This matches diagram 1. No problems here.