I believe it is analyzing influences :3
To prevent being under weight, you need to eat right. Providing your body with nutritions and protein
Its B. its easy if you take the time to think about it
There are a couple of risk lowering drugs you can take such as tamoxifen or raloxifene, or you can have a prophylactic mastectomy or a prophylactic oophorectomy.
Yes, exercise or any physical activity will help your mental health and stress your welcome ;)