Final answer:
The idea that one type of organism can evolve into another over time is encapsulated in Darwinism, based on the theory of natural selection and gradual change. The correct multiple-choice option is (b) Darwinism.
Step-by-step explanation:
The proposal that one type of organism can change gradually into another type over a long period of time is known as Darwinism. This concept is rooted in the theory of evolution by natural selection, as formulated by Charles Darwin. Unlike Lamarckism, which advocated for inheritance of acquired characteristics, Darwinism focuses on the gradual variation and selection of traits within populations over many generations, potentially leading to new species.
Darwinism is supported by the idea of gradualism, which suggests that small changes occur over long periods of time, as opposed to sudden, major changes advocated in catastrophism or non-scientific views like creationism.
The correct multiple-choice option is (b) Darwinism.