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.

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 GoldwaterNichols 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?
Secretary of the Army

Passage: By mid-1942, the Japanese found themselves holding a vast area from the Indian Ocean to the Central Pacific, even though they lacked the resources to defend or sustain it. Moreover, Combined Fleet doctrine was inadequate to execute the proposed "barrier" defence. Instead, Japan decided on additional attacks in both the south and central Pacific. While she had the element of surprise at Pearl Harbor, Allied codebreakers had now turned the tables. They discovered an attack was planned against Port Moresby; if it fell, Japan would control the seas to the north and west of Australia and could isolate the country. The carrier USS Lexington under Admiral Fletcher joined USS Yorktown and an American-Australian task force to stop the Japanese advance. The resulting Battle of the Coral Sea, fought in May 1942, was the first naval battle in which ships involved never sighted each other and only aircraft were used to attack opposing forces. Although Lexington was sunk and Yorktown seriously damaged, the Japanese lost the carrier Shoho, and suffered extensive damage to Shokaku and heavy losses to the air wing of Zuikaku, both of which missed the operation against Midway the following month. Although Allied losses were heavier than Japanese, the attack on Port Moresby was thwarted and the Japanese invasion force turned back, a strategic victory for the Allies. The Japanese were forced to abandon their attempts to isolate Australia. Moreover, Japan lacked the capacity to replace losses in ships, planes and trained pilots. Question: What American carrier was sunk in the Battle of the Coral Sea?
Lexington

Passage: In addition to the call buttons, elevators usually have floor indicators (often illuminated by LED) and direction lanterns. The former are almost universal in cab interiors with more than two stops and may be found outside the elevators as well on one or more of the floors. Floor indicators can consist of a dial with a rotating needle, but the most common types are those with successively illuminated floor indications or LCDs. Likewise, a change of floors or an arrival at a floor is indicated by a sound, depending on the elevator. Question: What type of lanterns are used outside elevators as well as inside most cabs?
direction lanterns