Select the best definition of Nephrotic syndrome.

A. A multisystem autoimmune disease associated with diverse autoantibodies and organ involvement. B. Acute pancreatic inflammation commonly presenting with severe epigastric pain and elevated pancreatic enzymes. C. Heavy proteinuria with hypoalbuminaemia, oedema and often hyperlipidaemia. D. Acute infection of the meninges requiring urgent antimicrobial treatment.