In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Among the entities, try to find the best entity that is most likely to fill in "_" and classify the answers based on options.

Baghdad, Iraq (CNN) -- A suicide bomber wearing an explosives-packed vest attacked a police recruitment center in northern Iraq Tuesday, a bloody strike that killed at least 65 people and wounded 160 others. The attacker -- who blew himself up when he was among hundreds of recruits -- staged the assault at a checkpoint where people usually wait their turn to enter the center. The explosion caused a fire at a fuel station nearby, police in Tikrit said, and most of those killed and wounded were young men who came to join police forces. Tikrit's general hospital was overwhelmed with wounded people, some of whom had to be sent to hospitals in nearby towns of the Salaheddin province and to other locations, such as Irbil and Kirkuk.Police say the attacker targeted police recruitsTikrit is nearly 100 miles north of BaghdadRecruitment centers have been frequently attacked 
 Questions:Mosques urged _ residents to donate blood for the wounded. (A) Baghdad (B) Iraq (C) CNN (D) Tikrit (E) Salaheddin (F) Irbil (G) Kirkuk
(D)

(CNN) Since the discovery of dark streaks on the slopes of Mars in 2011, astronomers have been excited about potential evidence of water beneath the surface of the red planet. If there are subsurface water flows on Mars, they could allow life -- even on a microbial level -- to exist as well. But further study of these recurring slope lineae, known as RSL, is revealing something else. Those dark streaks may be the result of granular flows like sand and dust, according to a study published Monday in the journal Nature Geoscience. The study is the product of a research team made up of representatives from the US Geological Survey, the Planetary Science Institute, the University of Arizona and Durham University in England.The flows correlate more with sand on active dunes rather than subsurface waterResearchers studied flows at 10 sites 
 Questions:Earth is the only analog we have for _, but Mars obviously behaves differently, the researchers said. (A) CNN (B) Mars (C) RSL (D) Nature Geoscience (E) US Geological Survey (F) Planetary Science Institute (G) University of Arizona (H) Durham University (I) England
(B)

(CNN) A group of 375 "concerned" scientists -- including famed physicist Stephen Hawking -- released an open letter Tuesday sharply criticizing Donald Trump, citing the threat of climate change and blasting his push for the US to leave the Paris Accord. "It is of great concern that the Republican nominee for President has advocated U.S. withdrawal from the Paris Accord. A 'Parexit' would send a clear signal to the rest of the world: 'The United States does not care about the global problems of human-caused climate change. You are on your own,'" the group wrote on the website responsiblescientists.org. The use of the term "Parexit" is a reference to a political withdrawal along the lines of the UK's vote to leave the European Union, commonly called the "Brexit."A group of scientists released an open letter on Tuesday urging action on climate changeThe scientists called for support of the Paris climate change agreement 
 Questions:CNN reached out to the _ campaign for a response to the letter, but did not immediately receive a response. (A) CNN (B) Stephen Hawking (C) Donald Trump (D) US (E) Paris Accord (F) Republican (G) U.S. (H) Parexit (I) United States (J) UK (K) European Union (L) Brexit (M) Paris

(C)