A 72-year-old vegan man presents with neuropathy and macrocytic anaemia. Laboratory tests show haemoglobin 100 g/L, MCV 112 fL, low serum vitamin B12, and elevated methylmalonic acid. What is the most appropriate treatment?AFolic acid supplementation aloneBVitamin B12 replacement with intramuscular hydroxocobalamin or high-dose oral cobalaminCIron supplementation onlyDNo treatment is required because he is asymptomaticELong-term prednisone therapyCheck my answer