Question

which of these led to the age of mammals?
adaptive radiation after the mass extinction of the dinosaurs
selective breeding done by humans hoping for better species
inbreeding of dinosaurs caused by a declining population

Explanation:

After dinosaurs went extinct, mammals had less competition and more ecological niches available, leading to adaptive radiation and the Age of Mammals. Selective breeding by humans came much later and in - breeding of dinosaurs is not related to the rise of the Age of Mammals.

Answer:

adaptive radiation after the mass extinction of the dinosaurs