Final answer:
HDL cholesterol is the class of serum lipid associated with a lower risk of heart disease due to its role in transporting excess cholesterol to the liver, helping to prevent arterial plaque buildup.
Step-by-step explanation:
The class of serum lipid that is associated with a lower risk of heart disease is HDL cholesterol. HDL, or high-density lipoproteins, play a crucial role in the body by transporting surplus cholesterol from bodily tissues back to the liver for recycling, thereby preventing plaque formation in the arteries. This function of HDL has earned it the nickname of "good cholesterol." Maintaining a high level of HDL is important for reducing the risk of heart disease. On the other hand, LDL or low-density lipoproteins, often referred to as "bad cholesterol," carry cholesterol from the liver to other tissues in the body, which can contribute to plaque buildup and increase the risk of heart disease if levels are too high.