Definition: 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.
Input: Question: Did Nantz join CBS sports before Billy Packer? Passage:Nantz joined CBS Sports in 1985, initially working as a studio host for the network's college football and basketball coverage, and as an on-course reporter for PGA Tour golf, as well as calling NFL games on Westwood One (from 1988 to 1990, when he was moved to television, Nantz called Sunday Night Football games for what was then called CBS Radio Sports). Nantz has anchored CBS' coverage of the Masters Tournament since 1989. He teamed with Billy Packer to call the NCAA Final Four men's basketball finals from 1991 until 2008. From 2008 to 2013, Clark Kellogg had been his analyst. From 2010 to 2013, Nantz and Kellogg were joined during the Final Four by Steve Kerr of TNT Sports. From 2013 to 2014, Greg Anthony partnered with Nantz. Following Anthony's suspension, Bill Raftery and Grant Hill were selected to replace him and are Nantz's new partners. Leading up to the Final Four, Nantz typically covers the games of the team awarded the overall #1 seed.
Links: a. Billy Packer b. PGA Tour on CBS c. Bill Raftery d. NCAA Division I Men's Basketball Tournament
Output:
a