Darwin began to formulate his concept of evolution by natural selection after a experimentation with animals. b reading the writings of Wallace. c observations of many species and their geographical locations. d agreeing with Lamarck about the driving force behind evolution.

c observations of many species and their geographical locations.

Explanation:

Darwin's theory of evolution by natural selection explains adaptation and speciation where the best-adapted organisms are more likely to survive. This theory was inspired by the observations made by Thomas Robert Malthus that noticed that the limitations of resources leads to survivance with the formation of new species s a consequence.

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