Select the best definition of Megaloblastic anaemia.

A. Diffuse hepatic fibrosis with regenerative nodules and altered liver architecture. B. A syndrome in which the heart cannot meet metabolic demands or does so only at elevated filling pressures. C. A macrocytic anaemia caused by impaired DNA synthesis, often from folate or vitamin B12 deficiency. D. Hyperglycaemia with ketonaemia and metabolic acidosis due to severe insulin deficiency.