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:
Doctor_Who

Context:
Doctor Who originally ran for 26 seasons on BBC One, from 23 November 1963 until 6 December 1989. During the original run, each weekly episode formed part of a story (or "serial") — usually of four to six parts in earlier years and three to four in later years. Notable exceptions were: The Daleks' Master Plan, which aired in 12 episodes (plus an earlier one-episode teaser, "Mission to the Unknown", featuring none of the regular cast); almost an entire season of seven-episode serials (season 7); the 10-episode serial The War Games; and The Trial of a Time Lord, which ran for 14 episodes (albeit divided into three production codes and four narrative segments) during season 23. Occasionally serials were loosely connected by a storyline, such as season 8 being devoted to the Doctor battling a rogue Time Lord called The Master, season 16's quest for The Key to Time, season 18's journey through E-Space and the theme of entropy, and season 20's Black Guardian Trilogy.

Question:
How many episodes were in The Daleks' Master Plan?

12