The answer is C - 30% according to most sports scientists.
Although eating fat doesn't sound very athletic, it is actually vital.
In fact, consuming enough calories from carbs and fat is important because it means protein consumption can be used for things that help athletes the most: muscle building and the production of enzymes, hormones and antibodies.
You can find a more detailed breakdown of the percentage of calories athletes should be taking from fat here: www.stockton.edu/ospreys/Nutrition/03/Fats2-03.htm but the answer you're looking for is within the 25-30% region, which matches with option C.
