The position of an object as a function of time is given by x = bt² - ct, where b = 2.0 m/s² and c = 6.7 m/s, and x and t are in SI units. What is the instantaneous velocity of the object when t = 3.3?

A) 9.1 m/s
B) 6.5 m/s
C) 7.8 m/s
D) 5.2 m/s