Which two sources contribute to the formation of blood?

The formation of blood in Traditional Chinese Medicine (TCM) is primarily attributed to the functions of the Spleen (SP) and Stomach (ST) in conjunction with Kidney (KD) essence. The Spleen plays a critical role in the transformation and transportation of nutrients from food, which are essential for generating Blood. It is considered the source of Qi and Blood production, emphasizing its importance in digestion and nutrient absorption.

Furthermore, Kidney essence is seen as a foundational element that supports overall vitality and is integral in nourishing the Spleen. This essence provides the necessary substance for the production of Blood, bridging the two roles of these organs in the process.

While the other options mention various organs and their functions, they do not align as closely with the traditional understanding of blood formation as the combination of Spleen and Kidney essence. Therefore, emphasizing the contribution of Spleen and Kidney essence reflects the essential processes involved in blood formation within TCM.