You are given a paragraph, a question and some answer options (associated with "A", "B", "C", "D", etc.) You need to list all the correct answer options with their associated letters (e.g. "A" can be a valid answer). Note that sometimes, more than one option can answer the question correctly and completely. In those cases, please generate all such options separated by a comma (e.g. "A, B" is a valid answer). Do not generate anything else apart from one or more of the following characters: 'A', 'B, 'C', 'D', etc.
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Question: Paragraph- Sent 1: The inhabited history of the Las Vegas Valley stretches to 23,000 b.c.
Sent 2: , when much of the area was covered by a prehistoric lake.
Sent 3: During this period, the indigenous people lived in caves, hunting the mammals that gathered at the shoreline.
Sent 4: The landscape of the valley changed dramatically over the next 200 centuries.
Sent 5: The glaciers feeding the lake melted away and the lake evaporated.
Sent 6: Fossils tell an obscure story of man's slow and sporadic development.
Sent 7: Around 3000 b.c.
Sent 8: , native Archaic Indians began to develop a lasting hunting and gathering culture.
Sent 9: By this time, the valley was in much the same geographic state as it exists in today, with one exceptionthe presence of artesian springs that bubbled to the surface in several areas.
Sent 10: These springs fed a network of streams draining through the Las Vegas Wash to the Colorado River.
Sent 11: The areas surrounding the springs were desert oases: sprawling collections of grasses, trees, and wildlife.
Sent 12: Many springs lay in areas that would eventually become the center of the modern Las Vegas metropolis.
Sent 13: For about 4000 years, the Archaics thrived in a culture that included many signs of early civilization.
Sent 14: Signs of even more advancement appeared halfway through the first millennium a.d.
Sent 15: , when the Anasazi Indians inhabited the valley.
Sent 16: Far more progressive than the Archaics, the Anasazi utilized such formal agricultural techniques as irrigation to assist their harvest.
Sent 17: This permitted the Anasazi to achieve a benchmark of advanced societythe ability to live in permanent shelters year-round without need to follow wildlife.
Sent 18: Mysteriously, the Anasazi vanished from the valley around a.d.
Question: Who was the most advance early civilization that disappeared in Las Vegas? (A) Cherokee (B) The Anasazi (C) Nez Perce (D) Archaics.

Answer: B.

Question: Paragraph- Sent 1: In Colombia, the drug-financed guerrillas trying to seize the country and destroy democracy include M-19, which Castro has clearly backed.
Sent 2: Robert Merkel, a former U.S. attorney handling drug indictments in Florida, doesn't think for a minute that Castro's much publicized trials of high officials engaged in the drug trade mean he has broken off with the Medellin drug cartel.
Sent 3: "If the cartel succeeds in blackmailing the Colombian authorities into negotiations, the cartel will be in control and Fidel can exploit his past relationships with them," he told the Journal's David Asman recently.
Sent 4: The struggle against the drug lords in Colombia will be a near thing.
Sent 5: This week, the government arrested Jose Abello Silva, said to be the fourth-ranking cartel leader.
Sent 6: He will probably be extradited to the U.S. for trial under an extradition treaty President Virgilia Barco has revived.
Sent 7: Later, another high-ranking trafficker, Leonidas Vargas, was arrested and 1,000 pounds of dynamite seized.
Sent 8: Mr. Barco has refused U.S. troops or advisers but has accepted U.S. military aid.
Sent 9: President Bush has agreed to meet within 90 days with Mr. Barco, President Alan Garcia of Peru and President Jaime Paz Zamora of Bolivia to discuss the drug problem.
Sent 10: It might not be a bad idea to do that sooner, rather than later.
Sent 11: After the Panama fiasco, they will need some reassurance.
Sent 12: Certainly, the Colombian press is much in need of that.
Question: Who said the cartel must not succeed in blackmailing the Colombian authorities into negotiations? (A) Former US Attorney (B) President Bush (C) The Journal's David Asman (D) Fidel Castro (E) Robert Merkel.

Answer: A, E.

Question: Paragraph- Sent 1: At the conference room table was White House Deputy Chief of Staff Joshua Bolten.
Sent 2: Bolten watched the exchanges and, after what he called "a quiet moment,"suggested that the Vice President get in touch with the President and confirm the engage order.
Sent 3: Bolten told us he wanted to make sure the President was told that the Vice President had executed the order.
Sent 4: He said he had not heard any prior discussion on the subject with the President.
Sent 5: The Vice President was logged calling the President at 10:18 for a twominute conversation that obtained the confirmation.
Sent 6: On Air Force One, the President's press secretary was taking notes; Ari Fleischer recorded that at 10:20, the President told him that he had authorized a shootdown of aircraft if necessary.
Sent 7: Minutes went by and word arrived of an aircraft down in Pennsylvania.
Sent 8: Those in the shelter wondered if the aircraft had been shot down pursuant to this authorization.
Sent 9: At approximately 10:30, the shelter started receiving reports of another hijacked plane, this time only 5 to 10 miles out.
Sent 10: Believing they had only a minute or two, the Vice President again communicated the authorization to "engage or "take out" the aircraft.
Sent 11: At 10:33, Hadley told the air threat conference call: "I need to get word to Dick Myers that our reports are there's an inbound aircraft flying low 5 miles out.
Sent 12: The Vice President's guidance was we need to take them out."Sent 13: Once again, there was no immediate information about the fate of the inbound aircraft.
Sent 14: In the apt description of one witness, "It drops below the radar screen and it's just continually hovering in your imagination; you don't know where it is or what happens to it."Sent 15: Eventually, the shelter received word that the alleged hijacker 5 miles away had been a medevac helicopter.
Sent 16: Transmission of the Authorization from the White House to the Pilots The NMCC learned of United 93's hijacking at about 10:03.
Sent 17: At this time the FAA had no contact with the military at the level of national command.
Sent 18: The NMCC learned about United 93 from the White House.
Question: What was the conversation between the Vice President and President about? (A) Who was behind the attacks (B) "No direct conversation between them" (C) When he would return to Washington (D) What to do with the low-flying plane (E) An Order to Shoot Down the Plane (F) "President was told that the Vice President had executed the order".

Answer:
B, D, E.