Flip a coin. If it's heads, take business law. If it is tails, don't take the course. See what the result is and how you feel about it. If you really are neutral, you shouldn't be worried about the result. But if you hesitate based on what the outcome is, you may have an underlying preference you should address.
As for CorpFin vs. Calc III, what will you value learning more? Did you do well in your previous business related courses? If not (and particularly in the business finance course), perhaps it makes sense to take the CorpFin class.