Step 1: Understand the concept
Saturated fats have no C=C bonds in their fatty acid chains and are solid at room temperature. Unsaturated fats have C=C bonds and are usually liquid oils.
Step 2: Check margarine
Margarine is produced by hydrogenating vegetable oils, which removes most double bonds. It therefore holds mainly saturated fats and is semi-solid.
Step 3: Check the oils
Olive oil is rich in oleic acid, which is monounsaturated. Safflower oil is rich in linoleic acid, which is polyunsaturated. Fish oil is rich in omega-3 polyunsaturated fatty acids.
Step 4: Conclusion
Margarine is the one with mainly saturated fats.
Final Answer:
Margarine is hydrogenated, so it is rich in saturated fat. This is option (A).
\[ \boxed{\text{(A) }\text{Margarine}} \]