Define acceleration and state SI unit for motion along a straight line, when do we consider the acceleration to be
(A) Positive
 B. Negative
Give example of a body in uniform acceleration

Hint Generally, positive means positive graph we will get and negative means negative graph we will get so here something it’s increasing or decreasing
As it relates to the velocity so as it increases it becomes faster so accelerates

Complete Step by step solution
First of all we need to think that what do you generally mean by acceleration
When the velocity of a body is increasing the body is said to be accelerating
Acceleration of the body is defined as the rate of change of its velocity with time
Acceleration = change in velocity / time taken for change $a = \dfrac{{v - u}}{t}$
$a = \dfrac{{v - u}}{t}$
 Where a is the acceleration
v is the final velocity
u is the initial velocity
t is the time taken
SI unit of acceleration is $m/s_{}^2$$m/s_{}^2$
It is a vector quantity .
So coming to the next part:
There are two types of acceleration positive and negative
If the velocity of a body increases the acceleration is positive
And if the velocity of a body decreases acceleration is negative
Negative acceleration or deceleration is also measured in the same way as positive
Example
1. A ball being hit by the tennis racket both the ball’s speed and direction is changing
Now example of uniform acceleration
2. THE MOTION OF FREELY FALLING BODY
3. The motion of bicycle going down the slope when the rider is not pedalling

Additional information
When a body is moving with the uniform velocity its acceleration will be zero
A body is said to be uniform acceleration if it travels in a straight line and velocity increases by equal amounts in equal interval of time

Note

First I need to understand the trick that is the relation of positive and negative increasing and decreasing and uniform means everything needs to be equal and perfect.