Answer:
C. Roberto se lo dedica.
Step-by-step explanation:
A is incorrect for a simple reason. You can't use to pronouns that start with l next to each other. My teacher always explained it as you can't lay low (le lo) in Mexico.
B is incorrect because it is the first one that is changed to se.
C. Is correct because of the reasons above.
D is incorrect because adding the el libro at the end makes it repetitive and unnatural. It is literally saying Roberto dedicated it, the book, to him. Which, if you already know from context what is being talked about, does not need to be mentioned.
Hope this help. I see there is in the picture you chose the right one, so nice job.