Hello, darkvelvet!
From your integral, I conclude that your graph is wrong.
And I don't agree with their answer.
The graph of is the upper half of a "horizontal" parabola,
. . vertex at (0,0), opening to the right.
The graph of is the above graph reflected over the axis.
The graph of is the same graph raised 2 units.
And is the axis.
The graph looks like this:
Code:

2 * *
 *
* *
 * *
 *.
 .::::*..
*:::::::::::*...
::::::::::::::::::::*.....
  *  +              *  
 1 4

My answer is 2.