I believe the right answer would be C) monitor.
Monitor can be a noun; "I have many monitors."
Or a verb; "I'll be able to monitor that soon."
I don’t understand the question, is there more context you can provide? A central claim is a statement asserting a belief provided with evidence
"tan bonito" does not make part of the sentence. The sentence is describing a girl, so instead it should say;
"tan bonita"