Final answer:
The colonists were unhappy about British restrictions on iron production in the colonies.
Step-by-step explanation:
The colonists were unhappy about British restrictions on iron production. In the colonies, there were limitations on manufacturing certain goods that were also produced in England. This included iron goods, which the colonists were prohibited from producing and selling. The British wanted to prevent the colonists from underselling English merchants and to control the trade relationship between the colonies and England.