TASK DEFINITION: This task is about writing a correct answer for the reading comprehension task. Based on the information provided in a given passage, you should identify the shortest continuous text span from the passage that serves as an answer to the given question. Avoid answers that are incorrect or provides incomplete justification for the question.
PROBLEM: Passage: The army is led by a civilian Secretary of the Army, who has the statutory authority to conduct all the affairs of the army under the authority, direction and control of the Secretary of Defense. The Chief of Staff of the Army, who is the highest-ranked military officer in the army, serves as the principal military adviser and executive agent for the Secretary of the Army, i.e., its service chief; and as a member of the Joint Chiefs of Staff, a body composed of the service chiefs from each of the four military services belonging to the Department of Defense who advise the President of the United States, the Secretary of Defense, and the National Security Council on operational military matters, under the guidance of the Chairman and Vice Chairman of the Joint Chiefs of Staff. In 1986, the Goldwater–Nichols Act mandated that operational control of the services follows a chain of command from the President to the Secretary of Defense directly to the unified combatant commanders, who have control of all armed forces units in their geographic or function area of responsibility. Thus, the secretaries of the military departments (and their respective service chiefs underneath them) only have the responsibility to organize, train and equip their service components. The army provides trained forces to the combatant commanders for use as directed by the Secretary of Defense. Question: Who does the Chief of Staff serve as the principal military adviser to?

SOLUTION: Secretary of the Army

PROBLEM: Passage: In 2010, a leaked cable revealed that Shell claims to have inserted staff into all the main ministries of the Nigerian government and know "everything that was being done in those ministries", according to Shell's top executive in Nigeria. The same executive also boasted that the Nigerian government had forgotten about the extent of Shell's infiltration. Documents released in 2009 (but not used in the court case) reveal that Shell regularly made payments to the Nigerian military in order to prevent protests. Question: A 2010 leaked communication revealed that Shell claimed to have inserted what into which entities?

SOLUTION: staff into all the main ministries of the Nigerian government

PROBLEM: Passage: One species in particular received widespread attention—the whooping crane. The species' historical range extended from central Canada South to Mexico, and from Utah to the Atlantic coast. Unregulated hunting and habitat loss contributed to a steady decline in the whooping crane population until, by 1890, it had disappeared from its primary breeding range in the north central United States. It would be another eight years before the first national law regulating wildlife commerce was signed, and another two years before the first version of the endangered species act was passed. The whooping crane population by 1941 was estimated at about only 16 birds still in the wild. Question: How many years after the noted absence of the whooping crane from its breeding range did the first law regulating wildlife commerce pass

SOLUTION:
eight years