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: Who is the person currently in Bob Sheets' 1989 position? Passage:"Hurricane!" (episode: 1616 (308)) is a Nova episode that aired on November 7, 1989 on PBS. The episode describes the fury of a hurricane and the history of hurricane forecasting. The episode features footage of Hurricane Camille of 1969 and Hurricane Gilbert of 1988 and behind the scenes footage at the National Hurricane Center as forecasters tracked Hurricane Gilbert from its formation to its landfall in northern Mexico. Meteorologists Hugh Willoughby, Bob Sheets (then director of the National Hurricane Center) and Jeff Masters were shown in the episode. The episode was released on VHS home video under the same episode title and distributed by WGBH Boston video. In 2004, the Nova episode was released on DVD and featured a different cover picture and title style. In 1997, UAV Corp. also distributed the Nova episode under the title "Deadly Hurricanes" which contains additional footage of Hurricane Andrew and Hurricane Iniki of 1992. The UAV version of the episode has since been discontinued.
Links: a. Nova (American TV program) b. VHS c. Bob Sheets d. National Hurricane Center
Output:
d