A 26-year-old pregnant female presents with persistent, dry, ulcerated skin over her knees and elbows for 8 weeks. Vital signs: BP 118/76, HR 88, RR 16, Temp 37°C, SpO2 98%. Examination reveals small, gray plaques on the conjunctiva bilaterally. She denies diarrhea or other GI symptoms. Recent serum retinol level is 28 μg/dL (normal >30). She takes prenatal vitamins without vitamin A supplementation. Which vitamin deficiency best explains her clinical findings?

1. A)Excessive cholecalciferol intake
2. B)Thiamine deficiency
3. C)Retinol deficiencyGABARITO
4. D)Excessive α-tocopherol intake
5. E)Ascorbic acid deficiency