The free body diagram of a structure when supports are removed should represent the forces and moments that remain. In this case, we are given that there is a 100kN force acting at a point, and we need to show the effects of this force in the absence of the supports. The correct representation is the one in option (A), where the forces acting on the structure are represented as arrows, showing the direction and magnitude of the forces. Option (A) is the correct free body diagram.
Final Answer: (A)