You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
American_Broadcasting_Company

Context:
The 1970s were highlighted by several successful comedy, fantasy, action and superhero-themed series for the network including Kung Fu, The Six Million Dollar Man, Wonder Woman, Starsky & Hutch, Charlie's Angels, The Bionic Woman, Fantasy Island and Battlestar Galactica. Many of these series were greenlit by Silverman, who left ABC in 1978 to become president of NBC's entertainment division. The rousing success of Happy Days also led to a successful spin-off series, Laverne & Shirley, which debuted in 1976. Charlie's Angels and Three's Company (which debuted in 1977) were two prime examples of a trend among the major networks during the 1970s known as "jiggle TV", featuring attractive, often buxom, women in main and guest roles.

Question:
What position did Fred Silverman leave ABC to take in 1978?

president of NBC's entertainment division