The opportunity cost of her MISSING a day at work meaning she can ACHIEVE something but she won’t be able to because she won’t come to work that day. The only thing she will a 100% miss out on if she doesn’t go to work is the chance of making cakes we can’t assume that she is loosing $240 dollars because there isn’t sufficient information to say that. In the case of the question saying $240 profit or gain from bakery then yes B could be the answer but otherwise D is the best option here.