What does “your choice stroke” mean

Typically there are four competitive strokes that will be used in our workouts.  Freestyle, Backstroke, Breaststroke, and Butterfly.  It is OK to not be able to do all of the strokes.  When a set is listed as “your choice stroke” you can use any of the competitive strokes or any instructional stroke such as sidestroke or elementary backstroke.   This option gives you the chance to individualize your workouts.