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: Biochemistry
All of the following are the reasons for impaired absorption of calcium except: 
Select and explain. 
A. Inositol hexaphosphate in cereals, B. High intake of oxalate, C. High concentrations of fatty acids in the intestinal lumen, D. Decreased iron intake
D: Decreased iron intake
Answer: D: Decreased iron intake 
Explanation: Phytic acid (inositol hexaphosphate) in cereals binds calcium in the intestinal lumen, preventing its absorption. Other minerals, including zinc, are also chelated by phytate. This is mainly a problem among people who consume large amounts of  unleavened  whole-wheat  products;  yeast  contains  an enzyme, phytase, that dephosphorylates phytate, so rendering it inactive. High concentrations of fatty acids in the intestinal lumen, as a result of impaired fat absorption, can also reduce calcium absorption by forming insoluble calcium salts; a high intake of oxalate can sometimes cause deficiency since calcium oxalate is insoluble.
HARPERS ILLUSTRATED BIOCHEMISTRY30th, Page No: 541