I keep getting "small" and "book" confused. Thanks Duo for putting them both in the same sentence so i could figure that out!
There isn't the option to write 읽어요 only 읽습니다.
both are correct! just different ways of saying it. you could consider 읽습니다 to be more formal, while 읽어요 is used more regularly.
This sentence was super hard for me. X.x