If Peter is successful in an action for damages against Super Market, it will probably be because?

Peter purchased a generic box of cereal from Super Market. While eating the cereal, Peter broke a tooth on a stone that was in the cereal. The generic cereal is provided to Super Market by three different companies: Branch, Mullen, and Ace. Each sells approximately equal quantities of cereal to Super Market. In addition, all the companies package their product in identical wrappers so that it is impossible to tell which of the companies furnished the box of cereal that Peter purchased. Although the companies compete with each other, at Super Market’s request they worked together to design the product wrapper. If Peter is successful in an action for damages against Super Market, it will probably be because:

a. Super Market, Branch, Mullen, and Ace were involved in a concerted action in the manufacture and marketing of the product.

b. Super Market, Branch, Mullen, and Ace established standards on an industry wide basis, which made identification of the product’s manufacturer impossible.

c. The negligence of Mullen, Branch, or Ace resulted in harm to Peter under circumstances such that it was impossible to tell which of them caused the harm.

d. One of the three companies, Mullen, Branch, or Ace, manufactured a defective product, and Super Market sold that product while it was in a defective condition.