What does lymph primarily consist of?

Lymph primarily consists of white blood cells and interstitial fluid. This fluid is derived from the blood and is the excess fluid that surrounds cells in tissues, which is collected and filtered through the lymphatic system. White blood cells within the lymph are crucial for the immune response, as they help to identify and fight infections and diseases. The combination of these components in lymph is critical for maintaining fluid balance in the body and for providing a pathway for the immune system to detect and respond to pathogens.

The other choices do not align with the composition of lymph. Red blood cells and platelets relate more to blood than lymph, while oxygen and carbon dioxide pertain to respiratory gas exchange and not lymphatic fluid. Glycogen and glucose are related to energy storage and metabolism, which are not constituents of lymph either. Thus, the presence of white blood cells and interstitial fluid defines lymph's role in immune function and fluid homeostasis.