Iodine is the main raw material for the synthesis of thyroid hormone. Lack of iodine in drinking water and food will lead to insufficient thyroid hormone secretion, which can easily lead to thyroid hyperplasia and enlargement, becoming endemic goiter, commonly known as big neck disease. Consuming iodized salt and eating iodine-rich seafood such as kelp and seaweed often can This disease can be effectively prevented.

So choose: D