The Massachusetts Government Act of 1774 significantly changed the governance of Massachusetts by limiting self-government and increasing British control. Among its key provisions, it effectively abolished the colonial charter and restricted town meetings, thereby undermining the local governance that had been in place. This act did not allow colonists to rule themselves; rather, it placed the government more directly under British authority.
From the options you provided, the most accurate statement regarding the Massachusetts Government Act is that it prohibited the colonial assembly, as it curtailed the powers of the elected colonial officials and interfered with the normal functioning of the government in Massachusetts. Additionally, while it did not specifically close Boston Harbor (that was a result of the Boston Port Act, another part of the Coercive Acts), it did set the stage for increased tensions and eventual conflict between the colonies and Britain.