当需求不变而供给发生变动时，若供给增加，则均衡价格下降，均衡产量会( )。

A．增加

B．减少

C．不变

D．无法判断

Seminiferous tubules contain all of the following components EXCEPT

A．Sertoli cells

B．Spermatocytes

C．A fibrous connective tissue tunic

D．Skeletal muscle in their tunica propria

E．A germinal epithelium