This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Growth, Development, and Behavior, Subject name: Pediatrics
Megaloblastic anemia, glossitis, pharyngeal ulcers, and impaired immunity. For each disorder above, select the dietary deficiency that is likely to be responsible. 
Select and explain. 
A. Folate deficiency, B. Thiamine deficiency, C. Niacin deficiency, D. Vitamin D deficiency
A: Folate deficiency
Answer: A: Folate deficiency 
Explanation: Folate deficiency can occur from a number of etiologies including poor intake or absorption; in high-demand diseases such as sickle cell; and in inborn errors of metabolism. It can also be seen in conjunction with a variety of medication uses including high-dose nonsteroidal anti-inflammatory drugs (NSAIDs), methotrexate, and phenytoin. Deficiency results in megaloblastic anemia, glossitis, pharyngeal ulcers, and impaired immunity.