Digit pattern counting — target 9 flanked by specific neighbors How many 9's in the sequence are immediately followed by 7 and immediately preceded by either 4 or 5? 1 2 3 7 8 9 1 4 9 7 3 6 9 8 1 5 3 5 9 7

Introduction / Context:
Again, a local-neighborhood scan. We look only at digit 9 and test its immediate neighbors.

Given Data / Assumptions:

• Sequence: 1 2 3 7 8 9 1 4 9 7 3 6 9 8 1 5 3 5 9 7
• Count 9's with left ∈ {4,5} and right = 7.

Concept / Approach:
List 9's positions: 6, 9, 13, 19 (1-based). Check neighbors.

Step-by-Step Solution:
Pos 6: left=8 ⇒ reject.Pos 9: left=4, right=7 ⇒ count.Pos 13: left=6 ⇒ reject.Pos 19: left=5, right=7 ⇒ count.

Verification / Alternative check:
Recheck indices carefully; only positions 9 and 19 qualify.

Why Other Options Are Wrong:
1 or 3/4 miscount the qualifying instances.

Common Pitfalls:
Counting a 9 where the follower is not 7.

Final Answer:
2