All potatoes naturally contain solanine, which is poisonous in large quantities. Domesticated potatoes contain only very small amounts of solanine, but many wild potatoes contain poisonous levels of solanine. Since most of the solanine in potatoes is concentrated in the skin, however, peeling wild potatoes makes them at least as safe to eat as unpeeled domesticated potatoes of the same size. Which one of the following, if assumed, allows the conclusion above to be properly drawn? ['Wild potatoes are generally much smaller than domesticated potatoes.', 'The amount of solanine concentrated in the skin of a wild potato is large enough by itself to be poisonous.', 'There are no poisonous substances in domesticated potatoes other than solanine.', 'There is no more solanine in a peeled wild potato than in an unpeeled domesticated potato of the same size.']