It is asking for the best "Spanish phase" so C is definitely not an option and B means "what is your name" and has nothing to do with asking someone for a favor. Hopefully, this is helpful. :)
The answer would be A because you are asking for a favor so por favor is used to ask for a favor not B because you don’t want to ask for someone’s name not C because you are just saving please or it can be both ways but we will choose A
