Correct Answer  Option 2 : 8
Given: 621754
By adding 2 in the even digits and subtracting 1 from the odd digits, we will get,
Number

6

2

1

7

5

4

operation

+2

+2

1

1

1

+2

New Number

8

4

0

6

4

6

Here can clearly says that 8 and 0 are not repeated.
Therefore, sum of the number = 8 + 0 = 8
Hence, "8" is the correct answer.