"The student is sleeping because it is Saturday."
Translation:Studentka śpi, ponieważ jest sobota.
Not only both, but all three: bo / ponieważ / dlatego, że. They all work.
Any of these three options is more formal or informal or it's just a choice of everyone?
"ponieważ" and "dlatego, że" sound... more serious than "bo". But I wouldn't call "bo" informal.
Isn't bo also because or is there some twich of grammar that it can't be used in this context? This frustrates me.