The answer is: a. Bob has committed the tort of unfair competition.
Tort of unfair competition is given to businesses practices that are believed to be adopting wrongful method/intention in order to economically damage other businesses or consumers.
What bob did to Alice is considered a wrongful intention and can be charged with the tort of unfair competition. One challenge that Alice might face in this situation is to proof that Bob indeed hurt her business because of their past relationship.