## Step 1: Analyze the Table The table explains how the universe behaves depending on what dominates it: - **Matter** and **radiation** both cause the universe’s expansion to *slow down* (decelerate), and their energy densities *decrease* over time. - **Dark energy** causes the universe’s expansion to *accelerate*, and its energy density remains *constant*. **Explanation:** If the universe is dominated by matter or radiation (stuff moving quickly or slowly), the expansion is *slowing*. Only with dark energy does the expansion *accelerate*. --- ## Step 2: Analyze the Answer Choices - **First option:** Says expansion accelerates with stuff moving quickly or slowly — this is incorrect, as only dark energy causes acceleration. - **Second option:** Says it contracts (slows) — the table says it expands, but the expansion slows, not contracts. - **Third option:** Says if the universe consists of stuff moving quickly or slowly (matter or radiation), it will expand but the expansion will slow — this matches the table. - **Fourth option:** Says if mostly dark energy, the density of matter would be constant — the table says only dark energy's density is constant. **Explanation:** The third answer directly matches the table: with matter or radiation dominance, the universe expands but its expansion slows. --- ## **Final Answer:** **If the universe consists of stuff that is moving either quickly or slowly compared to the speed of light, it will expand but the expansion will slow.**