Statement 1 tells us the number of integers in the set, but not the number of numbers being selected. The number selected affects the probability of them being selected in ascending order.
For instance, if only two were selected, the probability of the lower one being selected before the higher one would be .5.
If ten were selected, without doing the math you could tell that the probability of all of them being selected in ascending order would be much lower than .5.
Insufficient.
Statement 2 tells us how many are selected, 5. Because we know how many are being selected we don't need to know how many are in set A, as at least as many are in the set as are being selected.
Further, for the purposes of determining the probability of the ones selected being selected in ascending order, only the number selected matters. The rest of the members of the set do not affect the order of selection of those being selected.
There could be five numbers in the set, 1, 2, 3, 4, and 5, and we could select them, or there could be 1000 numbers in the set and we could still select five of them. Either way we would be selecting five numbers in ascending order or not in ascending order.
You could think of the selected numbers as lowest, second lowest, middle, second highest and highest. That holds no matter how many are in the total set. So what you are calculating is the the probability of picking the lowest first and the rest in ascending order.
Therefore, without doing any math we can see that we could calculate the number of possible arrangements of 5 numbers and that we could calculate the probability of their being selected in one particular arrangement, in this case in ascending order.
Sufficient.
The correct answer is B.
