Answer and Explanation:
The narrator of a "A Participant's First-Hand of Account the Boston Tea Party" describes two instances where citizens of Boston (Captain O'Connor and the tall, aged man) attempted to take tea of the boat for their own use rather than tossing it aboard as planned by the colonists. This angered the colonists because the plan was devised as a rebellion against Britain and the purpose was to prevent the taxed goods from entering the market. Stealing these goods rather than destroying them would contradict this purpose.
The quote that shows this purpose is in paragraph 2 of the account, "On the day preceding the seventeenth, there was a meeting of the citizens of the county of Suffolk, convened at one of the churches in Boston, for the purpose of consulting on what measures might be considered expedient to prevent the landing of the tea, or secure the people from the collection of the duty".
Note: "Collection of the duty" as used in this sentence is used to refer a tax on imported goods entering a market.