Beginning in 2011, Yemen was drawn into a civil war because of: O A. conflicts between Sunni and Shiite Muslims. O B. an American military invasion of the country. O c. territory being seized by ISIS terrorists. OD. Yemeni hostages being taken in Iran.​

i am confused, what is the question? i can you out if you put it into more depth.

the federal government of the united states was established by the constitution. us is a presidential republic. the president is head of state, head of government and of a two party legislative and electoral system. the supreme court balances the powers of the federal and the state government. yhe executive branch is headed by the oresident. there are two chambers of congress, the senate and the house of representatives. judicial power is exercised by the judicial branch (or judiciary), comprised of the supreme court and lower federal courts. the judiciary's function is to interpret the   constitution as well as the federal laws and regulations.

an informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.