The answer is D. letter A could increase the chance of injury, but not necessarily depending on other kinds of workouts available. Letter B is definitely not the answer because there can be many variations to make running a more enjoyable exercise. And C is not the answer because running is a great form of exercise for the body. the answer is D because cardio may increase the chances of leading to a heart attack.
Every cell in your body has the same genes/DNA but, the gene expression process decides which genes are active in which cells which is how each cell type gets it properties.