The velocity vector v of a particle moving in the xy plane is given by v = (5.5t - 5.0t²)i + 9.0j, with v in meters per second and t > 0. What is the magnitude of the particle's velocity when t = 2 s?
a) 11 m/s
b) 9 m/s
c) 7 m/s
d) 5 m/s