Of course you can choose for that. The babysitter will take care of your kid when you just don't have the time, but I highly recommend to let her parents (or another sim that lives on the same lot) look after her, too. The babysitter will take care of her, as I said before, but that is just all he or she does. When the baby grows up into a toddler, you need to read books with her yourself to give her a head start in some skills. Besides that, if you don't have the time for that, just let the little one play with the toys that give the kid some head start, too.