Which of the following does not represent a population?

a. all the robbins in austin, Texas
b. all the birds in Chicago illinois
c. all the grass frogs in the pond of central park, New York City
d. all the earthworms in Yosemite National Park

I would have to say B. Cause from what i remember from anthropology is that a species is a group of living organisms that sucessfully breed together. A population would then me a species that resides in a certain place. Therefore, robbins in texas is a population, grass frogs in New York are a population, and Earthworks in Yosemite are a population.
Leaving B out because it says all birds. And we know there are hundreds of bird species our there that do no all sucessfully breed together.