Explanation
To find the maximum number of green roofs, we need to test which houses can potentially have a green roof while following all the rules.
1. Analyze Given Fixed Data:
2. Check Potential for Other Houses (Applying Rule 4 - Neighbor Rule):
Rule 4 states that a house cannot share any color (roof or chimney) with its neighbor.
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House A: Neighbor to B. Since B uses Red (roof) and Black (chimney), A can have a Green roof as long as its chimney is not Green (chimneys are never green anyway) and not Black or Red (to satisfy neighbor rule with B). So, A can have a Green roof and White chimney.
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House C: Neighbor to B. Since B uses Red and Black, C can have a Green roof (with a White chimney).
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House D: Neighbor to C and E.
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If House C has a Green roof, House D cannot have a Green roof.
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If House E has a Green roof, House D cannot have a Green roof.
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Therefore, House D can never have a green roof in any scenario where E is green.
3. Evaluating the Combinations:
However, we must check if A and C can both be Green simultaneously.
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If A is Green and C is Green, House B is between them. House B is Red/Black, so there is no conflict between A-B or B-C.
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Can House E and House C both be Green? No. Because if C is Green, House D must use colors other than Green. But House E is Green, so House D cannot use Green anyway. The conflict is that if House C is Green, House D must pick a different color. If House E is Green, House D must also pick a different color. This is possible.
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Wait, check Rule 4 again: "No house may use any of the same colors that the every next house uses". If House C is Green, and House E is Green, House D is the neighbor to both. House D cannot use Green. This is perfectly fine.
4. Final Count:
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House A: Green (Possible)
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House B: Red (Fixed)
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House C: Green (Possible)
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House D: Yellow or Red (Possible)
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House E: Green (Fixed)
The maximum number of green roofs is 3 (Houses A, C, and E).
Correct Option:
(c) 3