Final answer:
The Magna Carta established that the king was subject to the rule of law, and that a free man could only be penalized after lawful judgment by his peers, laying a foundation for modern legal systems.
Step-by-step explanation:
The Magna Carta, signed by King John in 1215, is a cornerstone of modern legal principles, particularly due process. One key aspect of this historic document is that it codified the principle that a free man could not be penalized unless there had been a lawful judgment by his peers, establishing a precedent for trial by jury. The document's significance also lies in the fact that it subjected the king to the rule of law, indicating that even monarchs were not above the law.
Regarding the question at hand, the correct answer is D. That the king is subject to the rule of law. This idea was revolutionary at the time and laid the groundwork for the concept that all people, including the sovereign, were subject to the law. This paradigm shift was a significant step towards the systems of governance and legal protections we have today, influencing subsequent legal documents like the U.S. Constitution.