The correct option is C
Mutation theory of evolution
Ancon sheep were a group of domestic sheep with long bodies and very short legs which made them unable to jump fences. They appeared suddenly in 1791 in Massachusetts, USA due to random mutations that might have occurred in the germ cells of the parents and passed onto the offspring.
Hugo de Vries gave the mutation theory of evolution. He believed that new species evolved due to a single step large mutation known as saltation. Thus, the sudden appearance of a new species in a single generation substantiates the mutation theory of evolution given by Hugo de Vries.
Darwin’s theory of natural selection states that new variations appear in every generation. Such small variations accumulate over several generations by natural selection until the offspring become significantly different, thus evolving into a new species. Darwin believed that evolution is a gradual process unlike Hugo de Vries.
Neo-Darwinism (modern synthetic theory of evolution) is the integration of Darwin's theory of evolution by natural selection and Mendel's laws of inheritance.
Lamarck, a French biologist, believed that new characters are acquired by the organisms in order to adapt to the changes in the environment. The changes in the environment of an organism creates new needs in behaviour or structure in the organism that would help it to adapt better to the changing environment. This leads to the development of new characters which involve the greater use of some organs keeping it functional while disuse of certain organs leads to their size reduction and loss of functionality.