The twenty-first season of British science fiction television series "Doctor Who" began on 5 January 1984 with the 5th Doctor (Peter Davison) serial "Warriors of the Deep", and ended with Colin Baker's first serial "The Twin Dilemma". For only the second time (the first being during season 4), the entire TARDIS crew changed over the course of a single season.

Based on that paragraph can we conclude that this sentence is true?
Season 21 began in January of the 1980's for the show Doctor Who.
Yes