Final answer:
The passage from the Magna Carta refers to improving the Rights of merchants to safe conduct and trade, contributing to the principle that all, including monarchs, are subject to the law.
Step-by-step explanation:
Based on the passage from the Magna Carta, the basic rights that were improved by the English barons are the Rights of merchants to safe conduct and trade. The Magna Carta of 1215 is a foundational document in English legal history that laid the groundwork for the idea that everyone, including the king, is subject to the law. Among its provisions, the Magna Carta codified the principles of due process and established protections for life, liberty, and property.
It also set a precedent for the trial by jury system, which is integral to the judicial system in the West today. The specific passage addresses the rights of merchants, confirming their freedom to conduct business safely and according to traditional customs, with exceptions only in times of war.