Explanation:
we need to remember the squared numbers of the baud integers :
1² = 1
2² = 4
3² = 9
4² = 16
5² = 25
6² = 36
7² = 49
8² = 64
9² = 81
10² = 100
so, what squared integers are closest to 83 and 35 ?
well, 81 (9²) and 36 (6²).
so, the result has to be closest to 9 - 6 = 3.
83 is larger than 81 than 35 is smaller than 36. so, 3 is less than sqrt(83) - sqrt(35).
therefore, the correct answer is indeed 3.