Two Populations of Thsamspecies Havthsamimmigration, Emigration, Andeath Rates, Anthfemales in Each

Two populations of thsamspecies havthsamimmigration, emigration, andeath rates, anthfemales in each population producfour offspring on averagduring their reproductivyears.If thtwo populations havdifferent net reproductivrates, it is because

A) one population has more food than the other.
B) one population has less disease than the other.
C) one population breeds at a later age than does the other.
D) one population has more food than the other, and one population has less disease than the other.
E) one population has more food than the other, one population has less disease than the other, and one population breeds at a later age than does the other.