MSFinals-1350

A 50-year-old man with a history of chronic active hepatitis B presents with abdominal distension and bilateral ankle oedema, worsening over the previous 2 weeks. Three months ago, he was admitted for bleeding oesophageal varices, which was treated endoscopically. There was shifting dullness without tenderness on abdominal examination, and splenomegaly was also noted. His serum albumin concentration was diminished. Prothrombin time was elevated.
Which one of the following diuretics will best help this patient?