The correct option is
B Line 3
x and y said are to be in a proportional relationship, if
i) The ratio between y and x is constant.
ii) The graph of the function passes through the origin (0,0).
Let us consider
Line 1:
![](https://df0b18phdhzpx.cloudfront.net/ckeditor_assets/pictures/1420203/original_724815_1.png)
Slope is constant, as it is a straight line.
It does not pass through the origin (0,0).
Therefore, it does not represent a proportional relationship.
Let us consider
Line 2:
![](https://df0b18phdhzpx.cloudfront.net/ckeditor_assets/pictures/1420210/original_724815_2.png)
Slope is constant, as it is a straight line.
Thus it does not pass through the origin (0,0).
Therefore, it does not represent a proportional relationship.
Let us consider
Line 3:
![](https://df0b18phdhzpx.cloudfront.net/ckeditor_assets/pictures/1420211/original_724815_3.png)
Slope is constant, as it is a straight line.
It passes through the origin (0,0).
Therefore, it represents a proportional relationship.
Let us consider
Line 4:
![](https://df0b18phdhzpx.cloudfront.net/ckeditor_assets/pictures/1420450/original_123.PNG)
Slope is not constant as it is a straight line but at (1,20) slope becomes 0.
It also passes through the origin (0,0).
Therefore, it is not representing a proportional relationship.
So, only
Line 3 represents a proportional relationship.