The correct answer is (b) accumulation of variations over several generations.
Explanation:
Evolutionary theory posits that new species form through the gradual accumulation of genetic variations within a population over many generations. These variations can arise from mutations, natural selection, and genetic drift. When these variations become significant enough to prevent interbreeding with the original population, a new species is formed.
Why other options are incorrect:
(a) Sudden creation by nature:
This option contradicts the gradual nature of evolution. Evolution is a continuous process that requires time and natural selection to bring about significant changes.
(c) Clones formed during asexual reproduction:
While asexual reproduction can produce genetically identical offspring (clones), this does not lead to the formation of new species. Asexual reproduction does not introduce new genetic variations into the population, which is necessary for evolution to occur.
(d) Movement of individuals from one habitat to another:
Although migration can expose a population to new environmental pressures, this alone does not guarantee the formation of a new species. The change in environment must lead to the accumulation of genetic variations that result in reproductive isolation from the original population.