Refer to the following series and answer the question (all numbers are single digit numbers only).
(Left) 5 6 9 7 4 5 3 7 8 3 4 2 1 5 7 9 8 1 2 3 4 3 6 2 1 5 7 (Right)
How many such odd digits are there each of which is immediately preceded by an even digit and also immediately followed by an odd digit?
1
2
2
4
3
1
4
3