The successor of the largest 4-digit number of three different digit is

The correct option is D

none of these

The successor of the whole number means, If we add $1$ to the given whole number,we get its Successor

so, the largest 4 digit number is $9999$

$9999+1=10,000$ is Successor of $9999$

but it is not in three different digit

Thus Option D: none, is the correct answer.