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: Which former Digital Equipment Corporation who worked for Microsoft is the oldest? Passage:In November 1988, a new development team within Microsoft (which included former Digital Equipment Corporation developers Dave Cutler and Mark Lucovsky) began work on a revamped version of IBM and Microsoft's OS/2 operating system known as "NT OS/2". NT OS/2 was intended to be a secure, multi-user operating system with POSIX compatibility and a modular, portable kernel with preemptive multitasking and support for multiple processor architectures. However, following the successful release of Windows 3.0, the NT development team decided to rework the project to use an extended 32-bit port of the Windows API known as Win32 instead of those of OS/2. Win32 maintained a similar structure to the Windows APIs (allowing existing Windows applications to easily be ported to the platform), but also supported the capabilities of the existing NT kernel. Following its approval by Microsoft's staff, development continued on what was now Windows NT, the first 32-bit version of Windows. However, IBM objected to the changes, and ultimately continued OS/2 development on its own.
 Links: a. Software portability b. 32-bit c. 32-bit d. Dave Cutler
Example Output: d

Example Input: Question: Did the operation that Musicki contacted the Chetnik leader about actually take place? Passage:Mušicki was stationed in Slavonski Brod at the time of the Axis invasion of Yugoslavia in April 1941 and served as the Royal Yugoslav Army commander responsible for the railroad between Belgrade and Zagreb in the rank of colonel. He demonstrated his support for the Germans by helping their forces during the invasion. Yugoslavia was quickly conquered by the Axis powers and Mušicki remained in Slavonski Brod for several months after the conquest. He attempted to join the Ustaše Militia there, but was rejected. He went to Belgrade in mid-August, where he was received by Zbor leader Dimitrije Ljotić. On 6 October, Milan Nedić, the Prime Minister of the Axis-installed puppet Government of National Salvation, appointed Mušicki to lead the Serbian Volunteer Command (, SDK). Mušicki was involved in executing Serb civilians in the town of Čačak in December 1941. He and Milan Aćimović contacted Chetnik leader Draža Mihailović on 5 December, possibly in an effort to warn him in advance of the assault the Germans had planned, codenamed Operation Mihailovic. This action prompted the Germans to question Mušicki's loyalty. He was removed from command at the end of 1941 and imprisoned by the Germans, but was later freed at Nedić's intervention.
 Links: a. Royal Yugoslav Army b. Operation Mihailovic c. Dimitrije Ljotić d. Government of National Salvation
Example Output: b

Example Input: Question: How old was Greg Valentine when he defeated Hammer? Passage:After briefly continuing his tag team with Big Josh, Hammer returned to singles competition and faced Steve Austin for the World Television Championship on the January 12 episode of Main Event, but was unable to win the title. After the loss, Hammer competed sporadically throughout the rest of the spring (including a brief feud with JT Southern) before returning full-time in August 1992. Hammer would fall to Greg Valentine and Nikita Koloff before his push began to accelerate. In September he went on a ten match winning streak, defeating Dallas Page, Vinnie Vegas (Kevin Nash), and Super Invader (Hercules Hernandez). He received a US title shot against Rick Rude on the November 21st episode of WCW Power Hour but came up short. Hammer teamed with Erik Watts at Halloween Havoc and was victorious against The Vegas Connection. For the remainder of October and November he was strongly pushed, going 19-2 in a streak that included victories over Tony Atlas, The Barbarian, and Mustafa Saed. He would also team with Brad Armstrong in a brief feud with Page and Vegas.
 Links: a. Greg Valentine b. Hercules (wrestler) c. WCW World Television Championship d. Greg Valentine
Example Output:
a