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?

Given series: (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)

According to the question, such odd digit which are immediately preceded by an even digit and is immediately succeeded by an odd digit:

Required condition: Even digit - Odd digit - Odd digit

(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)

Thus, there are four such odd digit which are immediately preceded by an even digit and is immediately succeeded by an odd digit.

Hence, "Option 2" is the correct answer.