Missing graph. I attach it in the answer.
In a uniformly accelerated motion, the velocity at time t is given by:
where a is the acceleration and t is the time.
Given the previous equation, if we plot v(t) versus t, we find a straight line; moreover, a (the acceleration) represents the slope of the curve.
Looking at the graph, we see that when the time goes from 10 s to 20 s, the velocity increases from 4 m/s to 6 m/s. Therefore the slope of the curve is
and this corresponds to the acceleration.
So, the correct answer is <span>
0.2 m/s2.</span>