Your answer is C. Think of the x axis as the ground.
If you make the denominators all the same, the fractions are 3/12 , 3/12 , and 3/12. Then by simply adding them together you get that the mural is 9/12 painted. that then simplifies to 3/4 or 75%
Hope this helps :)
The answer is .5 cm. I hope it’s right