Question

If the yellow flags are flown on poles 1 and 6, which of the following must be true?

• A. \( \text{A green flag is flown on pole 4.} \)
• B. \( \text{A green flag is flown on pole 5.} \)
• C. \( \text{The white flags are flown on poles that are next to each other.} \)
• D. \( \text{A white flag and a yellow flag are flown on poles that are next to each other.} \)
• E. \( \text{Each white flag is flown on a pole that is next to a pole on which a green flag is flown.} \)

Hint:

Ensure green placement and restrictions.

Answer 1

The Correct Option is B

Step 1: Yellow on 1 and 6, 2 yellows used, 3 greens, 2 whites remain for poles 2, 3, 4, 5, 7.
Step 2: No green on 3, green cannot be adjacent, so 2 and 4, or 4 and 7, need spacing; 5 must be green to fit 3 greens.
Step 3: 5 not yellow-restricted, and 5G avoids adjacency (e.g., 2W, 3W, 4G, 5G, 7G works).
Step 4: All valid setups (e.g., 1Y, 2W, 3W, 4G, 5G, 6Y, 7G) require 5G, making (B) must be true.