Answer
See the graph below.
Work Step by Step
The ball goes through 3 stages of motion.
The first stage is when it is rolling without friction on the horizontal straight line at a constant speed which means that its acceleration is zero $a_{s1}=0$.
The second stage is when it is moving up the inclined surface and it slows down due to its weight component. Since the ball rolls without friction, so the only force exerted on it while it is moving up is its own weight (the gravitational pull). Hence, it slows down at a constant rate $a_{s2}=\rm Constant$ until it reaches the top surface.
The third stage, when it is moving at a constant speed again but its speed in this stage is less than its speed in the first stage. In this stage its acceleration is zero as well $a_{s3}=0$
