A Strict Vegan Diet Restricts the Intake of Meat, Eggs

A strict vegan diet restricts the intake of meat, eggs, milk, cheese, or other animal-derived foods. You are examining your patient who follows this particular dietary regimen. Urine analysis shows increased concentration of methylmalonic acid. This finding is indicative of which of the following?

A) excess methylmalonate in the diet
B) fatty acid deficiency
C) folate deficiency
D) protein deficiency
E) vitamin B₁₂ (cobalamin) deficiency