What did darwin infer from his observations of organisms in south america and the galápagos islands? a. the organisms on the galápagos islands were virtually identical to mainland organisms. b. a small number of different plant and animal species had come to the mainland from the galápagos islands. c. the organisms on the galápagos islands were completely unrelated to mainland organisms. d. a small number of different plant and animal species had come to the galápagos islands from the mainland.

d. A small number of different plant and animal species had come to the Galápagos Islands from the mainland.

Explanation:

Darwin observed both similarities and differences between plants and animal species present in the Galápagos Islands and the mainland. He concluded that some of the populations of plant and animal species from the mainland fragmented into several subpopulations and arrived in the Galapagos Islands.

After volcanic separation of these islands from the mainland, these subpopulations of various species diversified to become adapted to the different sets of environmental conditions.