I suppose the answer that was led here is C, grilled. However, it's not necessary the best way to cook fish of all the ways one could cook fish. The two best ways to cook fish are poached and baked, both with no oil or cream, just spices if desired. When grilling, one risks getting grill marks, which are carcinogenic. Cooking with cream can be deleterious for those who are allergic to dairy, which, if you are in the US, is many people are we use A1 cows. Cooking with oil is not ideal for a variety of reasons: any generic vegetable oil will raise your level of omega 6s and has a moderate burn rate; olive oil or avocado oil are less inflammatory and have moderately higher burn rates, but increase the caloric intake (and become unhealthy if they begin to smoke). Fried foods, as well, are carcinogenic and have unhealthy fats.
My favorite way to cook fish is to use a ceramic non-stick pan, turn the heat quite high, put the fish face down on the pan for one minute, then place the fish face-up in the over on a non-stick pan at three hundred and seventy-five degrees for 6-12 minutes, depending on the fish.