I am thinking its D or A but it may be wrong
A Vitrectomy is the removal of the vitreous fluid of the posterior chamber of the eye and replacing it with a clear solution. This is often done in the posterior chamber because the vitreous humor sometimes get tangled with other major parts of the eye.
Yoyo dieting may cause weight gain as when you are finished with the yo-yo diet your metabolic system is slowed down and when you try to eat like a normal person again you will gain more weight sometimes even more than what you started with. atkins causes weight loss by putting your body into ketosis this causes your body to eat the fat you eat and causes weight loss is some cases it also kills brain cells and can cause mood swings as well as headaches
some of the highest carb foods are fruits diets that want high carbs only will be hard to follow because you can only eat those things
some health risks of being overweight would be heart failure strokes blood clots diabetes liver failure and many other conditions. refer to second question.