As we all know ,Columbus          America and Edison         light bulbs.

A．discovered ; invented

B．invented ; discovered

C．discovered ; discovered

D．invented ; invented

下列哪项不是由于人口激增造成的  [ ]

A．粮食短缺   

B．能源短缺   

C．物种灭绝加速  

D．人口寿命增加