Which act required legal documents to be printed on special stamped paper?

The correct answer is the Stamp Act. This act, enacted in 1765 by the British Parliament, mandated that many printed materials in the American colonies—including newspapers, legal documents, and pamphlets—must be produced on specially stamped paper produced in London, carrying an embossed revenue stamp. The purpose of the act was to raise revenue to help pay for British troops stationed in North America after the French and Indian War.

The imposition of this tax was particularly contentious because it affected a wide range of everyday documents and publications, making it directly visible to the colonists and leading to significant opposition. The Stamp Act contributed to a growing sentiment of discontent among the colonies, as they began to protest against taxation without representation, marking an important step toward the American Revolution.

In contrast, the other acts mentioned in the question, such as the Sugar Act and the Currency Act, dealt with different aspects of colonial economic regulation and taxation, while the Quartering Act focused on the housing of British troops, rather than the taxation of printed materials.