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.

Example Input: Question: How old was Sophie Okonedo the year that she appeared as Liz 10, in the episodes "The Beast Below" and "The Pandorica Opens"? Passage:Although Scream of the Shalka continues the narrative of the original 1963–89 programme and the 1996 television film, the show's 2005 revival ignored its events. The series was scripted by veteran Doctor Who writer Paul Cornell, with Richard E. Grant providing the voice for the Ninth Doctor. This performance followed years of rumours that Grant would play the Doctor in a film or new series, and indeed he had appeared as the "Conceited Doctor" in the Comic Relief special Doctor Who and the Curse of Fatal Death in 1999. Grant subsequently went on to appear in the revived television series of Doctor Who as a guest villain in 2012's "The Snowmen" and 2013's "The Bells of Saint John" and "The Name of the Doctor". The Doctor's companion for this adventure, Alison Cheney, was voiced by Sophie Okonedo who a year later would be nominated for an Academy Award for her performance in Hotel Rwanda. She also appeared in the 2010 series of Doctor Who, as Liz 10, in the episodes "The Beast Below" and "The Pandorica Opens". Derek Jacobi reprised his role as the Master in 2007's "Utopia". David Tennant appeared in a cameo role as the Caretaker, later being cast as the Tenth Doctor in 2005.
 Links: a. Tenth Doctor b. Sophie Okonedo c. The Pandorica Opens d. Utopia (Doctor Who)
Example Output: b

Example Input: Question: How old was the person George studied with at University of Michigan when George attended Muhlenberg College? Passage:At age 17 Miller began school-teaching to raise funds for higher education. In 1882 he entered Franklin and Marshall Academy, and progressed to Muhlenberg College in 1884. He received his B.A. in 1887 and M.A. in 1890. While a graduate student, Miller was Principal of schools in Greeley, Kansas and then professor of mathematics as Eureka College in Eureka, Illinois. He corresponded with Cumberland University in Lebanon, Tennessee for his Ph.D. in 1892. He then joined Frank Nelson Cole at University of Michigan and began to study groups. In 1895 he went to Europe where he heard Sophus Lie lecture at Leipzig and Camille Jordan at Paris. In 1897 he went to Cornell University as an assistant professor, and in 1901 to Stanford University as associate professor. In 1906 he went to University of Illinois where he taught until retirement in 1931.
 Links: a. Cumberland University b. Frank Nelson Cole c. Frank Nelson Cole d. Frank Nelson Cole
Example Output: b

Example Input: Question: Are Thornton and Elk Grove both in Sacramento County? Passage:The highway enters Sacramento County from the south near Thornton, then continues northward through the western edge of Elk Grove that is mostly uninhabited wetlands with the exception of Laguna West. As I-5 approaches the city limits of Sacramento near Freeport, it runs adjacent to the Sacramento River that is on the west. The river then makes an abrupt westward curve after which the highway is flanked by the south Sacramento neighborhoods of Pocket-Greenhaven on the west and Meadowview on the east. The river curves back and meets with I-5 again, closing up the Pocket area. The highway then continues along the west side of Land Park, passing by William Land Park and the Sacramento Zoo. As it reaches the southwest corner of the downtown grid, the highway has a full-service junction with the 50/Business 80 freeway, and also merges with California State Route 99 for a concurrency.
 Links: a. Elk Grove, California b. Meadowview, Sacramento, California c. Thornton, California d. Thornton, California
Example Output:
a