Answer- A. Transferrin receptor-1 iron responsive elements increase transferrin receptor mRNA concentration and synthesisIn iron deficiency anemia, transferrin receptor-I iron responsive elements increase transfetin receptor mRNA concentration and synthesis."The regulation of iron metabolism at the cytoplasmic mRNA level by interaction of iron regulalory protein (IRP-I) and the iron-responsive elements (IREs) to apoferritin mRNA and transferrin receptor mRNA. When the cytoplasmic iron concentration is low, IRP-I binds to the IREs of both mRNAs.