Final answer:
Olive oil is the best source of monounsaturated fatty acids among the options given.
Step-by-step explanation:
Olive oil (choice D) is the best source of monounsaturated fatty acids among the options given. Monounsaturated fatty acids are found in foods like olive oil, peanut oil, and avocado (source 1). These fats have one less hydrogen atom than saturated fatty acids, making them liquid at room temperature (source 2). Other sources of monounsaturated fats include nuts and seeds like almonds and pecans (source 3).