Which force exerts a torque about the hinge ab

The 20.0cm by 35.0cm rectangular circuit shown in the figure (Figure 1) is hinged along side ab. It carries a clockwise I = 4.90A current and is located in a uniform 1.00T magnetic field oriented perpendicular to two of its sides, as shown.

Part A. Which force exerts a torque about the hinge ab?

Part B. Calculate only the force that exert the torque mentioned in part A.

Part C. Use your results from part B to calculate the torque that the magnetic field exerts on the circuit about the hinge axis ab.