Let’s analyze each answer choice about rich clusters of galaxies, using what astronomers have found: ### A) "are more likely to contain giant elliptical galaxies than poor clusters" - **Explanation:** Rich clusters **do** tend to have many more giant elliptical galaxies, especially near their centers, compared to poor clusters (like our Local Group, which has mostly spirals and irregulars). - **Evidence:** Observations show that the **central regions** of rich clusters are dominated by massive elliptical galaxies, formed through galaxy mergers and interactions that are much more common in dense environments. ### B) "contain far more spiral galaxies in their central regions than elliptical galaxies" - **Explanation:** This is **incorrect**. The central regions of rich clusters are dominated by **elliptical galaxies**, not spirals. Spirals are more common in less dense environments (like the outskirts or in poor clusters). ### C) "contain mostly galaxies dominated by the light of young stars (stars formed recently)" - **Explanation:** This is **incorrect**. Most galaxies in rich clusters, especially ellipticals, have **old stellar populations** with little recent star formation. Spirals (with young stars) are rare in rich cluster centers. ### D) "are so big that there is a lot more space between the galaxies than in poor clusters like our Local Group" - **Explanation:** This is **incorrect**. Rich clusters are more crowded; the galaxies are **closer together** than in poor clusters. ### E) "are the only places in the universe where galaxies find a way NOT to collide" - **Explanation:** This is **incorrect**. In fact, **galaxy collisions are more common** in rich clusters because galaxies are packed closer together. --- ## **Step-by-step reasoning:** 1. **Rich clusters** have many, many galaxies (hundreds to thousands), while poor clusters (like the Local Group) have only a few. 2. **Interactions and mergers** are more frequent in rich clusters due to the higher density of galaxies. 3. **Elliptical galaxies** are formed often via mergers, so they are more common in rich clusters. 4. The **central regions** of rich clusters are dominated by **giant elliptical galaxies**. 5. **Spiral galaxies** (with lots of young stars) are less common in rich cluster centers; they are more often found in poor clusters or the outskirts of rich clusters. --- ## **Correct Answer:** **are more likely to contain giant elliptical galaxies than poor clusters** This matches what astronomers observe: **Rich clusters are more likely to contain giant elliptical galaxies than poor clusters.** --- ### **Summary Table:** | Choice | True/False | Reason | |--------|------------|--------| | A | True | Rich clusters = more giant ellipticals | | B | False | Central regions = ellipticals, not spirals | | C | False | Most cluster galaxies = old stars | | D | False | Rich clusters = more crowded, not less | | E | False | Collisions MORE likely in rich clusters | --- **Final Answer:** > are more likely to contain giant elliptical galaxies than poor clusters **Step-by-step reasoning above explains why!**