As a vegan i would recommend legumes such as lentils, beans, nuts and peas. if you are still a meat eater try to lower your income of meat and try to cut out red meat and pork as those are labeled carcinogenic foods meaning its like the same thing as smoking.
a, because exercise doesn't just aid the prevention of certain diseases, it helps prevent many diseases. i would've chosen d if it wasn't so specific but a is the correct answer.