Let me assume u r asking about qn 4 (since u didnt mention anything in ur post and there r more than one qn in ur jpg.).


first, let me give u a tip:

in reading motion graphs, it is all about the gradient. Meaning what kinda slope the graph has.


[1]
So for Fig. 2.20, the graph is a displacement-time graph,
its gradient is called velocity.

and for Fig. 2.21, the graph is a velocity-time graph,
its gradient is called acceleration.


[2]
If u see a horizontal graph line, it has no slope, like a flat road, very easy to walk along. This gradient is zero, no slope means zero gradient.

If u see a vertical graph line, it has a steep slope, like a vertical cliff, very difficult to climb up. This gradient is very high, so high that mathematicians give a number infinity. Which is a very HUGE number. SO this gradient is infinity.


[3]
Now if u see a graph line like CD, which makes roughly a 45 deg angle with the time axis, has a gradient between zero and infinity. And this gradient is neither increasing nor decreasing. So this gradient is constant.

Likewise, a graph line making an angle of 20 deg is less steep than the graph line making an angle of 45 deg. SO we say, the steeper graph line has a higher gradient than a gentle slope graph line. A 20-deg graph line has a smaller gradient than a 45-deg graph line.



Now back to qn 4

part(a)
From pt O to pt A, can u see the slope is getting steeper? From a flat surface to a vertical slope?
SO we say the gradient is increasing.

To be specific for:

Fig. 2.20, the gradient is called Velocity,
we say, from O to A, the velocity is increasing.
(extra: and an increasing velocity is known as acceleration (speeding up).)
So ans is: The car is moving with increasing velocity.

Fig. 2.21, the gradient is called Acceleration,
we say, from O to A, the acceleration is increasing.
So ans is: The car is moving with increasing acceleration.



now, part(b)
From pt A to pt B, can u see the slope is getting gentler? From a vertical slope to a flat surface?
SO we say the gradient is Decreasing.

To be specific for:

Fig. 2.20, the gradient is called Velocity,
we say, from A to B, the velocity is decreasing.
[extra: and a decreasing velocity is known as deceleration (or slowing down).]
So ans is: The car is moving with decreasing velocity.

Fig. 2.21, the gradient is called Acceleration,
we say, from A to B, the acceleration is decreasing.
So ans is: The car is moving with decreasing acceleration.


next, part (c),
From pt B to pt C, can u see the slope is zero? flat, or no slope at all?
SO we say the gradient is zero.

To be specific for:

Fig. 2.20, the gradient is called Velocity,
we say, from B to C, the velocity is zero.
(extra: and a zero velocity means not moving, OR the object is at rest.)
So ans is: The car is stationary Or The car is at rest.

Fig. 2.21, the gradient is called Acceleration,
we say, from B to C, the acceleration is zero.
(extra: and a zero acceleration means the object is moving And it is moving with a constant velocity.)
So ans is: The car is moving with a constant velocity.


finally, part (d),
From pt C to pt D, can u see the slope is not changing? It is not increasing? It is also not decreasing?
SO we say the gradient is constant.

To be specific for:

Fig. 2.20, the gradient is called Velocity,
we say, from C to D, the velocity is constant.
So ans is: The car is moving with a constant velocity.

Fig. 2.21, the gradient is called Acceleration,
we say, from C to D, the acceleration is constant.
So ans is: The car is moving with a constant acceleration.


hope this helps.