Final answer:
Olive oil is the most rich in unsaturated fats compared to butter, lard, and coconut oil, which contain more saturated fats. Monounsaturated fats in olive oil can improve heart health by bettering blood cholesterol levels.
Step-by-step explanation:
The substance most rich in unsaturated fats is olive oil. Unlike saturated fats, unsaturated fats are typically liquid at room temperature. These are predominantly found in plant-based products and are healthier for the heart compared to saturated fats, which are solid at room temperature and mostly come from animal sources.
Olive oil, in particular, is rich in monounsaturated fats, which contain one double bond in their molecular structure, making them liquid at room temperature and beneficial for improving blood cholesterol levels. In contrast, substances like butter, lard, and coconut oil contain higher levels of saturated fats, which are generally solid at room temperature and can contribute to the formation of plaque in the arteries, thus increasing the risk of heart disease.