Refer to the following series and answer the question (all numbers are single digit numbers only).
(Left) 6 4 5 7 8 4 6 3 1 4 1 2 7 4 9 1 5 3 6 1 1 (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:

6 4 5 7 8 4 6 3 1 4 1 2 7 4 9 1 5 3 6 1 1

Condition to be checked:

An odd digit that is immediately preceded by an even digit and immediately followed by an odd digit.

We need to find the pattern: Even Digit - Odd Digit - Odd Digit

Let's examine the series:

4 5 7 8 4 1 1 2 2 7 4 4 9 1 6 1 1 

The patterns that satisfy the condition are 4 5 7, 4 1 1, 4 9 1, and 6 1 1.

Thus, there are 4 such odd digits that satisfy the given condition.

Hence, "4" is the correct answer.