An object's position is given by s(t) = 3.16 m + 4.45 m/s t + 1.14 m - 3.56 m/s² t². What is its speed at t = 6.1 s?
a) 0 m/s
b) 4.45 m/s
c) 8.9 m/s
d) 12.35 m/s