What would you say to invite a good friend to a party?
a. ¿quiere va a la fiesta contigo ? b. ¿queremos venir de la fiesta contigo? c.¿quieres ir a la fiesta conmigo? *** d.¿quiere ir a la fiesta con usted ?

a-las

explanation:

its talking about multiple books

ah, so ustedes and nosotros are my 'go-to' if i am using spanish mainly in the states? interesting, but still slightly confusing, haha."

it seems that you are a little confused about subject pronouns. yo=i, tú/usted=you, nosotros=we, ustedes=you(plural), ellos/ellas=they.

in the case of vosotros, it is an informal replacement for "ustedes" in spain. similar to using "you all" in english.

even though it is not generally used in conversation outside of spain, it is used many times in literature. i would suggest having at least some familiarity to that form, at least to recognize what it is.