Option D, Oliver Cromwell was an enemy of the king, is the right answer.
As a strict Puritan Oliver Cromwell, served as the Lord Protector of the Commonwealth of England, Ireland and Scotland from 1653 until his death. In 1653, he dissolved the Rump parliament because of its failure in the implementation of the reforms. He implemented his own ways to rule. Therefore, he is best described as the enemy of the king.