Final answer:
The panda's elongated wrist bone, or "thumb," can be explained by Lamarck's theory as some pandas acquiring this trait through strenuous activity and passing it on to their offspring.
Step-by-step explanation:
The panda's elongated wrist bone, often referred to as a "thumb," can be explained by Lamarck's theory in the following way: Some pandas acquired "thumbs" through strenuous activity and then produced offspring with the same characteristic. According to Lamarck's theory, an organism can acquire new traits during its lifetime through use or disuse of certain body parts, and these acquired traits can be passed on to its offspring.
Learn more about Lamarck's theory and the panda's elongated wrist bone