Answer:
The line parallel to y – axis is x = 4. Thus option a is correct.
Solution:
Given, a set of options as linear equations.
We have to choose one which is parallel to the y – axis.
We know that, slope of y – axis is undefined.
As the required line is parallel to the y – axis, its slope should also be equal to slope of y – axis.
Now, let us check one by one option.
Now, a) x = 4

= undefined
Here slope of this line is undefined. Which means it is parallel to y – axis.
So, we got our required answer.
Hence, the line parallel to y – axis is x = 4 i.e. option a is correct.