A client is able to correctly perform a single leg dumbbell overhead press.

The NASM OPT model recommends increasing instability to progress stabilization demands, moving from stable → less stable → unstable environments. For a single leg dumbbell overhead press, the next stabilization progression is to maintain the single-leg position but place it on a BOSU ball, which significantly increases balance and proprioceptive challenges.

Increasing dumbbell weight (Option A) changes load, not stability. Standing in a staggered stance (Option B) reduces stability challenge compared to single leg. Standing with two feet on a BOSU ball (Option C) is unstable but less challenging than single leg on BOSU. Therefore, single leg on BOSU is the correct progression.