(4 points) Chemical elements are closely related to human health. Please associate the following elements with human health. Type of missing element &; niobium (Nb)

(1) Calcium mainly exists in

(1) Calcium mainly exists in human bones and teeth, and calcium deficiency is easy to cause osteoporosis and rickets.

(2) Iodine deficiency is the main component of thyroid hormone synthesis, and iodine deficiency can lead to goiter;

(3) Iron is the main component of hemoglobin synthesis, and iron deficiency is easy to cause anemia;

(4) Zinc affects physical development. Zinc deficiency can lead to loss of appetite, growth retardation and stunting, so it is easy to become a dwarf.