Answer:
The correct answer is D. Unitary systems are most commonly found in smaller countries because it is easier for a central government to maintain control of a small country.
Step-by-step explanation:
A unitary state is a form of state where power is concentrated and there is a single center of power that extends its actions throughout the territory of the respective state. This, through its agents and local authorities, delegates of that same central power. It can count on a single legislative apparatus that legislates for the whole country; a judicial power, which applies the current law to the entire territory of the State and within which a Supreme Court of Justice is established, which has jurisdiction at the national level; a single executive power, that is conformed by all the governors (president, governors, mayors, etc.); and a single political constitution, which governs all the territory and to which all the authorities and inhabitants of the State are subject.