The position of an object is, x= at³ - bt² + ct where a=4.1, b =2.2, c= 1.7 and x, t are SI units. What is the instant acceleration at t=4.3s?
a) 101.44m/s ²
b) 102.44m/s ²
c) 100.44m/s²
d) 103.44m/s ²