This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Iron deficiency anemia, Subject name: Pathology
The pathogenesis of hypochromic anemia in lead poisoning is due to - 
Select and explain. 
A. Lead blocks transferrin receptors of erythroid precursors, B. Binding of lead to transferrin, inhibiting the transpo of iron, C. Inhibition of enzymes involved in heme biosynthesis, D. Inhibiting breakdown of ferritin into hemosiderin
C: Inhibition of enzymes involved in heme biosynthesis
Answer: C: Inhibition of enzymes involved in heme biosynthesis 
Explanation: Iron should be combined with protoporphyrin to synthesize Heme. To synthesize protoporphyrin and combine it with iron, enzymes like ALA synthase, ALA dehydratase & Ferrochelatase are required. Lead inhibits heme synthesis by inhibiting enzymes ALA dehydratase & Ferrochelatase resulting in microcytic hypochromic anemia.