A patient with Type 1 Diabetes Mellitus presents with severe metabolic acidosis due to diabetic ketoacidosis. Which enzyme is a key regulatory step in gluconeogenesis that is inhibited by insulin and activated by glucagon, playing a crucial role in glucose production during this state?

✓ Correct Answer: Option C

Fructose-1,6-bisphosphatase is a key regulatory enzyme in gluconeogenesis. It catalyzes the irreversible hydrolysis of fructose-1,6-bisphosphate to fructose-6-phosphate. Insulin inhibits, while glucagon activates, this enzyme, thereby regulating glucose synthesis.