We define acceleration as the rate of change of the velocity
Thus, if you have positive velocity and positive acceleration, your <u>speed increases.</u>
If you have positive velocity and negative acceleration, your speed decreases.
Now you get the idea, we will see that the correct option is graph 1.
We know that the car moves towards the right (let's define this as "the car has positive velocity") and we also know that te car is slowing down constantly (thus the acceleration needs to be negative and constant).
By looking at the graphs, the only one with these properties is graph 1.
If you want to learn more, you can read:
brainly.com/question/12550364