Concept:Sovereignty means the supreme power and final authority of a state to govern itself without outside interference.
Explanation:Sovereignty is the defining feature that sets the state apart from all other political organisations.
It gives the state ultimate control over its internal affairs, such as making laws and enforcing order.
It also gives the state independence in external affairs, meaning no foreign power can overrule it.
Other organisations, like political parties or pressure groups, only have limited or delegated authority.
In contrast, the state exercises the highest power, and its authority is absolute within its territory.
Therefore, the ultimate source of power and authority of the state is known as sovereignty.
Constitutionalism, checks and balances, and rule of law are important principles, but they are not the source of the state's supreme power.
Answer:Option D. Sovereignty.