Your foot is in contact with the ground and the ground reaction force is 723 N directed upwards. The mass of the foot is 1.2 kg, and it is undergoing acceleration of +5 m/s2 in the i direction and -13.2 m/s2 in the j direction. The net force acting on the foot in the x-direction is closest to:

a) 825.6 N
b) 717.6 N
c) 520.8 N
d) 371.4 N