Final answer:
The Magna Carta was a political document signed in 1215 by King John, which limited the monarchy and established trial by jury and due process for the nobles. Therefore, the correct option is B. King John
Step-by-step explanation:
The Magna Carta was a significant political document signed in 1215 by King John. It established the relationship between the king and the nobles in England and limited the monarchy.
The Magna Carta also guaranteed trial by jury and due process for the nobles, which helped establish a clearer legal system in England.