Sophie uses the word "because" to buy time, much like other people use "um" or "like" or "you know".
us: Sophie, please go put the books in your room.
SJ: no, because.... someone might want to read them.
us: Sophie, please finish your dinner.
SJ: no, because.... I won't be hungry for a 'zert. (dessert)
us: Sophie, did you just empty my jewelry box?
SJ: yes, because.... I need a necklace for my mermaid kingdom.
You get the idea.