Final answer:
The primary function of Leukemia Inhibitory Factor (LIF) is regulation of stem cell differentiation.
Step-by-step explanation:
The primary function of Leukemia Inhibitory Factor (LIF) is Regulation of stem cell differentiation. LIF is a cytokine that plays a crucial role in the maintenance and self-renewal of embryonic stem cells. It regulates the fate of stem cells by promoting their differentiation into specific cell types.