关于月经，错误的是（）

A.月经是指有规律的、周期性的子宫出血

B.月经是生殖功能成熟的外在标志之一

C.有月经表示有排卵

D.第一次来潮月经称月经初潮

E.月经血的特点是不凝固

Compared to European put options on an asset with no cash flows, an American put option: （）

A. will have a higher, lower bound on its price.

B. will have a lower, lower bound on its price.

C. will have the same lower bound on its price.