If 1 is added to each even digit and 2 is subtracted from each odd digit in the number 37846592, what will be difference between the highest and second lowest digits in the number thus formed? 

Given: 37846592

Add 1 to each even digit and subtract 2 from each odd digit.

3 → odd → 3 − 2 = 1

7 → odd → 7 − 2 = 5

8 → even → 8 + 1 = 9

4 → even → 4 + 1 = 5

6 → even → 6 + 1 = 7

5 → odd → 5 − 2 = 3

9 → odd → 9 − 2 = 7

2 → even → 2 + 1 = 3

New number: 1, 5, 9, 5, 7, 3, 7, 3

Now arrange the digits in ascending order:
1, 3, 3, 5, 5, 7, 7, 9

Highest digit = 9

Second lowest digit = 3

Difference = 9 − 3 = 6

So, 6 will be difference between the highest and second lowest digits in the number thus formed.

Thus, correct option is (a).