Is lymph more similar to blood plasma or interstitial fluid?

Lymph is more similar to interstitial fluid.

Lymph is the fluid that circulates through the lymphatic system, which is a network of vessels and nodes that helps to collect and filter waste products from the tissues. Interstitial fluid is the fluid that surrounds cells in the body. Both lymph and interstitial fluid contain water, electrolytes, proteins, and other solutes. However, lymph contains more proteins and fewer electrolytes than interstitial fluid. This is because lymph is filtered through the lymph nodes, which remove some of the electrolytes and water from the fluid.