A 55 kg person runs with a velocity of 4.5 m/s along a tangent to a stationary circular platform. What is the magnitude of the person's angular momentum with respect to the center of the platform?

a) 121.5 kg m²/s
b) 175.5 kg m²/s
c) 235.5 kg m²/s
d) 289.5 kg m²/s