The statement that flexibility is the capacity to move a joint through its full range of motion is true. According this definition flexibility training includes stretching exercises to lengthen the muscles. Each part of the body may have a different range of motion (ROM) or a different level of flexibility. Generally, stretching (static, dynamic or active isolated stretching) will help you improve your flexibility.
D wpuld be the best answer because dieting is the most important thing when losing weight. If she does add weight training the body fat will decrease and turn into lean muscle.