Final answer:
Unsaturated fats are most susceptible to rancidity due to their carbon-carbon double bonds. Antioxidants can prevent this process.
Step-by-step explanation:
Unsaturated fats are most susceptible to rancidity because they contain many carbon-carbon double bonds. These double bonds are susceptible to oxidation, which leads to the breakdown of the fats and the release of hydrogen peroxide, causing a bad odor and taste. Antioxidants like vitamin E and vitamin C can help prevent rancidity by inhibiting the oxidation process.