A bird flying due east. Its distance from a tall building is given by () = 20.0 +
(12.4 ^−1 ) − (0.035 ^−3 )^3
. What is the instantaneous velocity of the bird when t=8s? A. 16.12 m/s B. 17.12 m/s C. 18.12 m/s D. 19.12 m/s