**Core Concept:** Omega-3 fatty acids are polyunsaturated fatty acids (PUFAs) with an odd number of carbon atoms in their hydrocarbon chains. They include eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Omega-3s play a crucial role in maintaining cardiovascular health, neurodevelopment, and inflammation regulation.

**Why the Correct Answer is Right:** The correct answer is "D." Omega-3 fatty acids are essential nutrients for human health, primarily due to their anti-inflammatory and anti-thrombotic effects. They are involved in modulating eicosanoid production, particularly prostaglandins and leukotrienes, which contribute to inflammation and blood clot formation.

**Why Each Wrong Option is Incorrect:**

A. Omega-3 fatty acids are not only beneficial but also necessary for human health, as they cannot be synthesized by the body and must be obtained from diet or supplements.
B. Although omega-3s are crucial for cardiovascular health, they are not harmful in normal dietary intake.
C. Omega-3 fatty acids play a role in neurodevelopment and mental health, supporting cognitive function and preventing neurological disorders.

**Clinical Pearl:** The importance of omega-3 supplementation in preventing and treating various diseases, including atrial fibrillation, depression, and Alzheimer's disease, highlights the need for a balanced diet rich in fish, flaxseed, and walnuts, or regular omega-3 supplementation for optimal health.

**Correct Answer:** D. Omega-3 fatty acids are not harmful in normal dietary intake.