Final answer:
Transformationalism, also related to Lamarckism, is best summarized by answer choice (a) stating heritable changes occur due to use or disuse of specific body parts. This idea is now majorly debunked. So the correct answer is Option A.
Step-by-step explanation:
The now refuted idea of transformationalism is best summarized by answer choice (a). Transformationalism, also commonly associated with the theory of Lamarckism proposed by Jean-Baptiste Lamarck, posits that the use or disuse of a specific body part results in heritable change of that body part. For instance, if a giraffe consistently stretches its neck to reach leaves on taller trees, Lamarck proposed that change (lengthened neck) could be passed on to subsequent generations of giraffes. However, in the light of modern genetic research, this concept has been mostly refuted.
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