D because the y-intercept is at -5 like shown in the equation, and the slope equals to 1, and I do believe that the bold line means that it is less than or equal to, just like the equation says.
This is only my opinion. I could be wrong.
My guess is:
Somebody else used that book before you, maybe last year or
the year before, and it was somebody who didn't mind writing
in his book.
One day he didn't have time to write down the homework in his
assignment notebook, so he just circled the homework problems
in his textbook.
If the square and equilateral triangle have the same side length, a square would have a larger area.
Use these are equations and you can see which one is greater.
Square area with side length s: s^2
Equilateral triangle area: s^2 * (√3 ) / 4
(√3) / 4 < 1, if you didn't know
I hope this helps. Have an awesome day! :)