This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Where is the gene for folate carrier protein located on? 
Select and explain. 
A. Chromosome 10, B. Chromosome 5, C. Chromosome 21, D. Chromosome 9
C: Chromosome 21
Answer: C: Chromosome 21 
Explanation: . Chromosome 21