Bone fractures and torn ligaments are not the effects of extreme weight loss, and are rather the aftermath of trauma to the ligaments and bones. Stomach aches and severe thirst can definitely be caused, as your body will not be used to this new weight, especially after being an athlete. Again, osteoporosis is not usually the effects of these sort of things, it is mostly when the body may fail to form enough new bone, or too much old bone may be reabsorbed. Amenorrhea is can also be excluded from the causes of extreme weight loss.
So I would say, it is C.
