Which of the following is not considered a healthy fat

Idk what the options are but It might be trans fat and saturated fat.

Your question doesn't show options but the most unhealthy fat is trans fat, you can identify which foods have trans fats by looking at the ingredient list for ingredients that are "partially hydrogenated" the nutritional info will usually list the trans fat content as 0grams, but you have to look at the serving size and ingredients