Answer:
a) Linear equation
Step-by-step explanation:
Definition of acceleration
![a=(dv)/(dt)\\](https://img.qammunity.org/2020/formulas/physics/college/kxglq2mzlmt345222au80p86vhs85s89mt.png)
if a=constant and we integrate the last equation
![v(t)=v_(o)+a*t](https://img.qammunity.org/2020/formulas/physics/college/61et32igvrna55p3n37lhoe5is44h9egc5.png)
So the relation between the time and the velocity is linear. If we plot the velocity in function of time, the plot is a line, and the acceleration is the slope of this line.