A 70-yeаr-оld wоmаn with Pаrkinsоn disease (Hoehn and Yahr Stage 3) is referred to physical therapy after two falls in the past month. Both falls occurred when she was bumped by her grandchild while standing in the kitchen. She did not take a step to recover her balance in either instance. Her Berg Balance Scale score is 42/56, and her Mini-BESTest score is 16/28 with the lowest scores on the reactive postural control section. Using the ANPT balance diagnosis framework, which balance diagnosis is MOST appropriate?