Answer:
c. sus
Explanation:
The correct answer should be sus because that is the possessive adjective for ellos/ellas/ustedes. Mis is the possessive adjective for yo, but the sentence is not talking about themselves. The speaker is talking about other boys, or ellos. Additionally, it is sus and not su because the object (escritorios) is plural.
El -arbitro- es imparcial y justo.
