1) Exercise it by singing and hitting different notes, however don't go overboard
2) Make sure you don't overuse your voice, as well as trying to rest your voice when you are sick
3) Overall, have healthy habits, like not smoking and drinking a sufficient amount of water.
I would have to go with B) because the government doesn't do A and C in every place but they do make sure all food products are safe (FDA)
Hope This Helps :)
B. Asian, they’re known to have liver cancer better than any of the other race