A journalist is writing an article about five historical figures—A, B, C, D, E. She plans to mention them in five distinct paragraphs, one figure per paragraph. The order of mention must conform to the following conditions: 1. A must be mentioned immediately before C. 2. D must be mentioned in an earlier paragraph than B. 3. E cannot be mentioned in the first paragraph. 4. If B is mentioned in the fifth paragraph, then D must be mentioned in the second paragraph. If C is mentioned in the fourth paragraph, which of the following must be true?

Why the other options are wrong

• A. E could be in the fifth paragraph, as shown in the example (D, B, A, C, E), but it doesn't *have* to be. E could be in the second slot (D, E, A, C, B).
• C. B could be in the fifth paragraph, but it doesn't *have* to be. For example, B could be in the second paragraph if D is in the first. If A is 3 and C is 4, D is before B. E cannot be 1. So (D, B, A, C, E) is possible, with B in 2.
• D. D could be in the first paragraph, but it doesn't *have* to be. For example, D could be in the second paragraph if B is in the fifth. (E, D, A, C, B) is possible if E is not 1 (but it is). So E cannot be 1. Let's try to fit D in first. (D, E, A, C, B). This is possible. But D doesn't *have* to be first. D could be 2, then B is 5. (E, D, A, C, B). This is also possible. Wait, E cannot be 1. So D cannot be 2 if B is 5. So, if A is 3, C is 4. This means slots 1, 2, 5 are open. D is before B. E cannot be 1. If B is 5, then D must be 2. This leaves E for 1. But E cannot be 1. So B cannot be 5. Therefore, A is 3, C is 4, B is not 5. D is before B. E is not 1. The remaining slots are 1, 2, 5. D, B, E must fill these. D must be before B. E cannot be 1. So E must be 2 or 5. If E is 2, then D is 1. B is 5. This arrangement is (D, E, A, C, B). This is valid. If E is 5, then D is 1, B is 2. This arrangement is (D, B, A, C, E). This is also valid. So D does not *have* to be 1.