1 kg object is moving on a horizontal frictionless surface. Its displacement from the origin is given by the equation: x = 3.5 cos[π/2 t + π]. Where is the equation of the acceleration as a function of time?
A. a = 8.63 sin[(π/2) t + π]
B. a = -8.63 cos[(π/2) t + π]
C. a = -8.63 π cos[(π/2) t + π]