Which substance acts as the medium for exchanging oxygen and nutrients in the body?

The correct answer is blood. Blood serves as a vital transport medium in the body, playing an essential role in the exchange of oxygen and nutrients with tissues. It consists of various components, including red blood cells, which carry oxygen from the lungs to the tissues, and plasma, which contains nutrients, hormones, and waste products.

Through the circulatory system, blood delivers oxygen and essential nutrients to cells throughout the body and helps remove carbon dioxide and metabolic waste. This complex system ensures that all body tissues receive the necessary substances for survival and functioning.

While plasma is a component of blood and does carry some nutrients, it does not function independently as the medium for nutrient exchange throughout the entire body. Bile, on the other hand, is involved in digestion and the emulsification of fats but is not related to nutrient and oxygen transport. Interstitial fluid is found between cells and can also facilitate nutrient and waste exchange on a local level, but it relies on the circulatory system's blood to supply and remove these substances effectively.