1. what is the plural form of libro?

A. libros

b. libroes

c. libroces

d. libriones

The plural form of libro is A. libros.

If this is Spanish, you get the plural of a noun by adding the suffix - s to the end of the word. There is no need for changes such as adding - es as often happens in English. And C and D are just silly answers.

Its A my dude goodluck