Sentence Correction

The best strategy for preventing hip fractures among residents of geriatric homes is to eliminate hazards from the residential environment before bone-loss develops, combined with balance training and to encourage an increase of bone-density through diet and weight-bearing exercise.

MASTER GMAT:
A) to eliminate hazards from the residential environment before bone-loss develops, combined with balance training and to encourage an increase of bone-density through diet and weight-bearing exercise

B) to eliminate hazards from the residential environment and a combination of balance training to encourage an increase of bone-density through diet and weight-bearing exercise, before bone-loss develops

C) if hazards are eliminated from the residential environment and combined with balance training and to encourage an increase of bone-density through diet and weight-bearing exercise, before bone-loss develops

D) to eliminate hazards from the residential environment and, combined with balance training, to encourage an increase of bone-density through diet and weight-bearing exercise, before bone-loss develops.

E) if before bone-loss develops, residents combine balance training and encourage an increase of bone-density with diet and weight-bearing exercise while residential environments are eliminated of hazards.

please explain why b is wrong .
OA D