Thyroid hormone regulates human metabolism, growth and development, and improves the excitability of nervous system. Too little thyroid hormone secretion in childhood will lead to dementia, too much will lead to hyperthyroidism, and long-term iodine deficiency in the body will lead to endemic goiter, which is called big neck disease. Too little growth hormone secretion in childhood can lead to dwarfism. The similarity between dwarfism and dwarfism is short stature, but the difference is that dwarfism has low intelligence and dwarfism has normal intelligence. Therefore, a person is short when he is an adult.

Therefore, choose: B.