从生物学角度看，下列诗句中表现为竞争关系的是[ ]

A．兰溪三日桃花雨，半夜鲤鱼来上滩

B．种豆南山下，草盛豆苗稀

C．满园春色关不住，一枝红杏出墙来

D．人间四月芳菲尽，山寺桃花始盛开

The charity sale our school organizes every year has taught us much that we would never have________ learned in class.

A．therefore

B．meanwhile

C．otherwise

D．instead