The correct answer is indeed option C. "A rebellion in Scotland weakened the king, who was suspected of supporting the rebels". The civil war in England took place between the supporters of the monarchy of Charles I and his son Charles II and opposing groups in each of Charles’s kingdoms, including English Parliamentarians and Covenanters in Scotland. The previous victory of Covenanters during their rebellion in Scotland was one of the main reasons that led to England's civil war.