If 1 is added to each odd digit and 2 is subtracted from each even digit in the number 7645238, what will be difference between the highest and second lowest digits in the number thus formed?

Given: 7645238

Add 1 to each odd digit

Subtract 2 from each even digit

7 is odd → 7 + 1 = 8

6 is even → 6 - 2 = 4

4 is even → 4 - 2 = 2

5 is odd → 5 + 1 = 6

2 is even → 2 - 2 = 0

3 is odd → 3 + 1 = 4

8 is even → 8 - 2 = 6

So, the new digits are: 8, 4, 2, 6, 0, 4, 6

Now arrange them in ascending order: 0, 2, 4, 4, 6, 6, 8

The highest digit is 8
The second lowest digit is 2

So, the difference between the highest and the second lowest digits is:

8 - 2 = 6

Thus, correct option is (b).