Missing graph. I attach it in the answer.
In a uniformly accelerated motion, the velocity at time t is given by:
![v(t)=at](https://img.qammunity.org/2019/formulas/physics/middle-school/tqlnxavkh3rjp191fajzm21qmphfd86jzq.png)
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
![a= (\Delta v)/(\Delta t)= (6 m/s-4 m/s)/(20 s-10 s)= (2 m/s)/(10 s)=0.2 m/s^2](https://img.qammunity.org/2019/formulas/physics/middle-school/6ivrb6dgm20nz1m1slb69anwzxwm5ejrqe.png)
and this corresponds to the acceleration.
So, the correct answer is
0.2 m/s2.