The theory of common descent states that all modern organisms                   . a. can change in response to environmental change; b. descended from a single common ancestor; c. descended from one of many ancestors that originally arose on Earth; d. have not evolved; e. can be arranged in a hierarchy from 'least evolved' to 'most evolved'

Verified step by step guidance

1. Identify the key term in the question, which is 'common descent'. This term refers to the idea in evolutionary biology that all organisms on Earth are descended from a common ancestor.
2. Review each answer choice in the context of the definition of common descent. Consider how each choice relates to the concept of all organisms having a shared origin.
3. Evaluate choice (a) by considering if the theory of common descent specifically addresses organisms changing in response to environmental changes, or if this is more related to the concept of natural selection.
4. Analyze choice (b) to determine if it directly states that all modern organisms descended from a single common ancestor, which is the fundamental idea of common descent.
5. Assess choices (c), (d), and (e) to see if they align with the principle of common descent or if they introduce concepts that diverge from the main idea of a single common ancestor.