Refer to the given series and answer the question below (all numbers are…

Concept: In a number-series neighbour-condition question, every digit position is checked against its immediate left and right neighbours. The target pattern here is [Odd digit] - [Odd digit] - [Even digit]: an odd digit is counted only when the digit immediately before it is also odd AND the digit immediately after it is even. Checking both neighbour conditions together (not just one) avoids over- or under-counting when the same digits repeat elsewhere in the series.

Application: The series is: 3 7 4 5 2 4 8 4 9 4 2 1 5 3 4 6 2 1 5 7 3 7 5 9 8 5. Scanning left to right and checking every odd digit against both neighbour conditions:

1. 3 - 7 - 4: 7 is odd, its left neighbour 3 is odd, and its right neighbour 4 is even -> match.

2. 5 - 3 - 4: 3 is odd, its left neighbour 5 is odd, and its right neighbour 4 is even -> match.

3. 5 - 9 - 8: 9 is odd, its left neighbour 5 is odd, and its right neighbour 8 is even -> match.

4. Every other odd digit in the series fails at least one of the two neighbour conditions -- either its left neighbour is even, or (as with the long odd run near positions 19-24) its right neighbour is also odd -- so it is not counted.

Cross-check: Re-scanning the series a second time confirms the same three positions and no others, so no match was missed or double-counted.

The series contains exactly three numbers that are preceded by an odd number and followed by an even number.