According to Lamarckism, long necked giraffes evolved because
A. Nature selected only long necked ones
B. Humans preferred only long necked ones
C. Short necks suddenly changed into long necks
D. Of stretching of necks over many generations by short necked ones

Hint: The theory of Lamarckism was given by a French naturalist Jean Baptiste de Lamarck. It is a theory of evolution which is based on the principle of physical changes occurring in an organism during its lifetime.

Complete Answer:
- The theory of Lamarckism is also known as inheritance of acquired characters. It was given by Jean Baptiste Lamarck. He also put forward several evolution theories. Lamarckism says that an organism can pass on to its offspring physical characteristics that the parent organism acquired through use or disuse during its lifetime.
- He put forward an example of a long neck in giraffes. He said that the ancestors of giraffes had small necks and forelimbs as those like horses. They were residing in places where food was not available on the surface. To get food they had to stretch their limbs and neck. This led to elongation of the parts. This acquired physical feature was transmitted to other generations and so on.
- Theory of natural selection was put forward by Darwin.

Thus, the correct answer is (D). Of stretching of necks over many generations by short necked ones.

Note: The traits are transferred from one generation to another by the help of genetic material according to Mendellian genetics. Thus theory of Lamarckism does not fully explain the inheritance of the acquired traits.