Precursors for Gluconeogenesis

During fasting, the human body undergoes several metabolic adaptations to maintain blood glucose levels and provide energy to essential tissues. Hormonal regulation plays a crucial role in these adjustments, particularly involving insulin and glucagon. One key metabolic pathway activated during fasting is gluconeogenesis, which synthesizes glucose from non-carbohydrate precursors.

Considering the metabolic pathways involved, which of the following substrates can primarily serve as a precursor for gluconeogenesis in the liver?