A fisherman patient with burning sensation, dry tongue, pale tongue, bleeding erythematous gingiva. Which nutrient is deficient?

The presentation: PALE TONGUE + BURNING TONGUE + ERYTHEMATOUS BLEEDING GINGIVA = VITAMIN C (ASCORBIC ACID) DEFICIENCY = SCURVY. Classic scurvy signs: swollen/bleeding/red gingiva ('scurvy gums'), petechiae, poor wound healing, fatigue. Pale tongue can suggest anemia (also in scurvy). The BLEEDING GINGIVA + erythema is the KEY sign pointing to Vitamin C deficiency (collagen synthesis is impaired). Thiamin deficiency causes beriberi/Wernicke's. B12 deficiency causes neurological issues and megaloblastic anemia. D is correct.