关于肾上腺髓质，哪项错误（）。

A.主要由嗜铬细胞和少量交感神经节细胞组成

B.分泌肾上腺素和去甲肾上腺素

C.肾上腺皮质对髓质细胞的激素生成无影响

D.肾上腺素细胞多于去甲肾上腺素细胞

In launching a lifeboat，when should the tricing pendants be released?（）.

A.Before the boat is lowered from the stowage position

B.As soon as the boat-fall blocks clear the davit head

C.After the limit switch is activated

D.After all people have been embarked