Which of the following choices is true of darwin's theory of natural selection?
1points

a
his theory stated that all the species of life that existed in his time were the same as when life first emerged.

b
it was based solely on his observations made during his visit to the galapagos islands.

c
his theory stated that any change to a species was caused by humans using artificial selection.

d
his theory stated that the organisms best suited to their environment produce more offspring, causing the species to change over time.