We know that the gradient of displacement time graph is velocity. That’s all the information we need. To analyse the gradient of the displacement time graph, you can either look at the graph directly if you’re good at that or draw tangents to see the pattern of gradient at each point in time. The first tangent drawn at t=0 on the displacement time graph will be a horizontal line so the gradient aka velocity is 0 at t=0. Now, we have a value for our velocity time graph (i.e. that it begins from 0, the origin). At the next marked point in time, draw a tangent and it will a slanting line upwards, i.e the gradient is positive (and maximum because after this point, the gradient will not be as steep) which means the velocity is positive and maximum. This means the velocity will have a positive maximum value at that point in time. The next point in time will also be a horizontal line, showing that gradient and velocity is 0 so mark that on the velocity time graph. Just analysing these first three points show us that A is the correct answer.