In which badminton court the first serve for the serving side begins in doubles play, and why?

The answer to this is C. This means that either service court can start the serve. This is because the serving rotation will change depending on the team and the player who will first serve on the set. Each team will decide who among them will serve first.

The player can be on the left side or the right side. It will ultimately depend on what the team will decide on. This is the time when the players can be more strategic about how they are going to play. The better the choices that they make, the more chances that they are going to win against their opponent.