The answer is A
Consider any three digit number which doesn't have the last digit as 0.
Stmt1 if you add 9 to the number the tens digit becomes 3.
So the tens digit of the number must be 2. Because if you add 9 to the units digit - 1 would get carried over and the tens digit will become 3.
For eg. lets say our number is 525, now if you add 9 to it you get 534.
You can try this for any three digit number but the tens digit has to be 2.
For eg. 521+9, 526+9, 921+9, 225+9.....
The importance of the unit's digit not being 0 is that - if the number was 520 and you added 9. you'll get 529....
>>The tens digit of k has to be 2. stmt1 is suff.
Stmt2 - the tens digit of k+4 is 2
Doesn't give a conclusive answer - lets say the number k is 524 and we add 4, we get 528.
But if the number k is 517 and we add 4 we get 521.
So adding 4 may or may not have an impact on the tens digit. Which is not the case if you add 9 (in that case 1 has to carry over)
>> we can't be sure of the tens digit of k. stmt2 is insuff.
Not sure if that was the greatest explanation...but hope it helps!