Danny Ainge picked up options on two of his young stars-in-the-making on Tuesday. It was probably one of the easier decisions Ainge has made in recent months, exercising the team’s third-year option on guard Jaylen Brown and fourth-year option on guard Terry Rozier. Both players, two of the four returning Celtics from last season, have been counted on to play a bigger role this year, and both have lived up to the challenge so far this season. Brown has struggled with consistency as of late, but has started all seven games for Boston and averaged 15.4 points and 5.9 rebounds.