Question Author
You confuse me, Jenny. I should have thought the most "reliable source" regarding a biblical story would have been the Bible itself! Yet, the major Bible translation into English makes no mention of the Samaritan's profession at all, as I said above and earlier when the question was posted on AnswerBank.
Have I misunderstood or am I to gather from your response that you created the quiz concerned? If so, I'd still be delighted to find out which source said he was a merchant, if you know the answer to that.
(Thanks for the other answers, ladies.)