The correct option is B Lamarck
Lamarck suggested that changing environments lead to changes in the use or disuse of a body part/organ. These changes would be inherited by the offspring. He explained this theory using the example of giraffes, which were originally short-necked animals, but through continuous attempts to reach out to higher trees for leaves to eat, kept exerting pressure on their necks. Over generations, the length of the neck kept increasing, eventually resulting in the present day long-necked giraffes. He thus postulated the first functional theory on evolution.