Final answer:
The nobility of England showed their discontent with extra taxation by rebelling against King John and forcing him to address their demands in the Magna Carta.
Step-by-step explanation:
The nobility in England showed their discontent with extra taxation by taking action against King John. In 1215, several northern barons led a rebellion against the king, which quickly spread throughout the country. After months of negotiations, King John agreed to address the demands of the nobility, resulting in the signing of the Magna Carta. The Magna Carta laid out specific grievances and established the principle that all English citizens, including the king, are subject to the rule of law.