Preventable communicable, or infectious, diseases like malaria and HIV/AIDS account for millions of deaths in the world each year, especially in low-income countries. Noncommunicable, or chronic, diseases like heart disease and diabetes are having an increasing effect across the globe.
They will need medical help.
I think C. You can't have just proteins or no fats in your diet. It needs to be balanced with a little of everything.
I think one thing you could do in order to measure your cardiovascular strength you can do a full sprint run. In order to help improve your fitness levels you can swim, jog/run, body weight exercises, and a balanced diet.