The world’s population is getting larger and larger, so scientists will have to ______ new ways to solve food problem.

A．catch up with

B．keep up with

C．come up with

D．make up with

观察鸡卵结构图，若该卵已受精，则②号结构为

A．胚盘，色浅而小

B．胚盘，色浓而略大

C．胚胎，色浅而小

D．胚胎，色浓而略大