A particle travels in a circular orbit of radius r = 60.7 m. Its speed is changing at a rate of {dv}{dt} = 11.7 m/s² at an instant when its speed is v = 36.3 m/s. What is the magnitude of the acceleration at that instant?
a) 17.1 m/s²
b) 9.6 m/s²
c) 11.7 m/s²
d) 7.8 m/s²