Which of the following is most likely to concern an investor evaluating a corporation’s shareowner rights provisions（）

A. Shareowners may nominate board members.

B. Shares held by the founding family have supernormal voting rights.

C. To ensure accuracy, company executives tabulate and verify shareowner voting.

人体内激素分泌量过多或不足都会对机体有害，体内有一系列机制维持激素在血液中含量的相对稳定。下图表示下丘脑神经分泌细胞、垂体细胞、甲状腺细胞及它们分泌的激素之间的关系。据图回答有关问题：

激素A是（）