Constitutional Government means

Constitutional government (constitutionalism) is a system in which the authority of the state is defined, distributed, and limited by a constitution — a body of fundamental rules that every organ of government is bound to obey. Its essence is limited government under the rule of law, as opposed to arbitrary or absolute power.

Tested against this idea, each of the listed statements describes a genuine and essential dimension of such a government:

• It is government carried on according to the terms and limits of the constitution — the state may act only within the powers the constitution grants.

• It rests on the rule of law — public power is exercised through law rather than the arbitrary will of rulers, and no one stands above the law.

• In its modern form it is exercised through democratic authority — the government derives from, and is accountable to, the people within the constitutional framework.

Because each statement captures a real and essential facet, and no single one conveys the whole meaning, the complete answer is that all of these together describe a constitutional government.