**Core Concept**
Polyunsaturated fatty acids (PUFAs) are a type of essential fatty acid that are crucial for various bodily functions, including the formation of cell membranes, the production of eicosanoids, and the regulation of inflammation. PUFAs are characterized by the presence of multiple double bonds in their fatty acid chain.

**Why the Correct Answer is Right**
PUFAs are divided into two main categories: omega-3 fatty acids and omega-6 fatty acids. Omega-3 fatty acids, which are essential for heart health and brain function, have more than 50% of their fatty acid chain as double bonds. Omega-6 fatty acids, which are involved in the production of eicosanoids, also have a significant percentage of their chain as double bonds. However, the specific percentage can vary depending on the type of PUFA.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not specify a particular type of PUFA, making it unclear whether it meets the criteria.
* **Option B:** This option is incorrect because it is a type of saturated fatty acid, which does not have double bonds in its chain.
* **Option C:** This option is incorrect because it is a type of monounsaturated fatty acid, which has only one double bond in its chain.

**Clinical Pearl / High-Yield Fact**
It's essential to note that the human body cannot synthesize PUFAs de novo and must obtain them through the diet. A balanced diet rich in omega-3 and omega-6 fatty acids is crucial for maintaining optimal health.

**Correct Answer:**
D.