Final answer:
The Tea Act of 1773 controlled the sales and trade of tea in the colonies, giving a monopoly to the British East India Company. The colonists were unhappy because it reduced their profits and violated their rights.
Step-by-step explanation:
The British Act that controlled all sales and trade of tea was called the Tea Act of 1773. This act granted a monopoly to the British East India Company, reducing the profits of colonial merchants and cutting them out of the tea trade. The colonists were unhappy with this act because it deprived them of economic opportunities and represented a violation of their rights, particularly the idea of 'no taxation without representation.'