If all members of a species cannot produce offspring then that species will likely become extinct, and passenger pigeons are extinct. Given these facts, what could not produce enough offspring among the following options:
- Deoxyribonucleicacid
 - killer whales
 - Echinoids
 - single-celled organisms
 - sparrows
 - great white sharks
 - passenger pigeons
 - one celled organisms


 

       passenger pigeons  