In this task, you're given a question, a context passage, and four options which are terms from the passage. After reading a passage, you will get a brief understanding of the terms. Your job is to determine by searching and reading further information of which term you can answer the question. Indicate your choice as 'a', 'b', 'c', or 'd'. If you think more than one option is plausible, choose the more probable option to help you answer the question.
Q: Question: What is the capital of the European country that al-Bahri traveled through on his way to Afghanistan? Passage:Nasser al-Bahri (1972 26 December 2015), also known by his kunya or nom de guerre as Abu Jandal "father of death" or "the killer", was a member of al-Qaeda in Afghanistan from 1996 to 2000. According to his memoir, he gave his bayat (oath of allegiance) to Osama bin Laden in 1998. He was in al-Qaeda for six years as one of bin Laden's twelve bodyguards, A citizen of Yemen born in Saudi Arabia, al-Bahri was radicalized in his teens by dissident Saudi Ulemas and participated in clandestine political activities which were funded in part by people trafficking. Determined to become a jihadist, he went first to Bosnia and then, briefly, to Somalia before arriving in Afghanistan in 1996 in the hope of joining al-Qaeda, which he soon did. After four years, al-Bahri became "disillusioned", largely because bin Laden consolidated al-Qaeda's relationship with the Taliban by giving his bayat to its leader, Mullah Omar, but also because he had married and become a father.
Links: a. Bay'ah b. Bosnia and Herzegovina c. Bay'ah d. Ulama
A:
b