NANP Board Practice Exam

The correct answer is the one indicating that oleic acid has 18 carbons and 1 double bond. Oleic acid is a monounsaturated fatty acid, meaning it contains one double bond in its carbon chain. Specifically, it has a total of 18 carbon atoms, which is characteristic of this fatty acid.

The double bond in oleic acid is located at the ninth carbon from the methyl end of the fatty acid chain, which is why it's classified as an omega-9 fatty acid. The structure of oleic acid underscores its role in human nutrition, commonly found in various oils such as olive oil and canola oil, known for their health benefits.

The other options present incorrect configurations of carbon atoms and double bonds for oleic acid or refer to different fatty acids entirely. Hence, the specifications of 18 carbons and 1 double bond accurately reflect the characteristics of oleic acid.