I REALLY NEED HELP WITH THIS!! Please

1. Calculate the acceleration of this object from t=4~9 seconds

A. 19m/s^2
B. 6m/s^2
C. 3m/s^2
D. 0m/s^2

2. What is the objects acceleration at t=10 seconds?

A. 0m/s^2
B. 6m/s^2
C. -6m/s^2
D. Impossible to calculate

3. When did this object changed directions?

A. It did not change direction
B. At t= 6 seconds
C. At t= 11 seconds and At t= 14 seconds
D. At t= 4 seconds