Correct Answer - Option 2 : 651442
In the given coded form:
The numbers are first decreasing and then increasing by 1
4 - 1 = 3
5 + 1 = 6
8 - 1 = 7
6 + 1 = 7
9 - 1 = 8
3 + 1 = 4
Similarly,
742351 will be coded as 651442
Hence, 651442 is the coded form.