Why do persons with anaemia are adviced to eat iron reach food?

The correct option is B It helps in binding of oxygen.
A person with anaemia is adviced to eat iron rich food. Because, iron is very important for proper functioning of the haemoglobin protein present in red blood cells (RBC). Iron is integral part of haemoglobin protein. It binds to oxygen molecules and helps RBC transport to other parts of the body. It doesn't helps in increasing the RBCs but helps in maintain the proper functioning. And, iron do not help in fighting microbes inside our body.