At the start of a symphony performance, it is most likely that the movement will be B. The movement will be slow and serious. Typically, symphonies begin with an introduction that sets the tone for the piece. This introduction is often characterized by a slower tempo and a serious mood, allowing the audience to settle in and prepare for the musical journey ahead.
As the symphony progresses, it may transition to different tempos, dynamics, and moods, showcasing the composer's creativity and the orchestra's versatility. However, the initial moments of a symphony performance often lean towards a more deliberate and contemplative start before building up to more lively and dramatic sections later on.