X= { 11, 13,17......97}
y= {5,15,25........95 }

let the combined new set be z, thus Z= {5, 11,13,15.......97}
and its range will be 97-5 =92

Set X = {11, 13, 17,............., 83, 89, 97}
Set Y = {5, 15, 25,..............., 75, 85, 95}

Combining two sets, say Set Z

Set Z = {5, 11, 13, 15, 17, 25,..................., 75, 83, 85, 89, 95, 97}

Range = Max Value - Min Value
Range (Z) = 97 - 5 = 92

OA D is the answer.

Solved the answer correct here and clicked the answer wrong.

first odd multiply of 5 is 5
the last 2 digit prime is 97
97-5=92

Try this, it mostly relies on using the answers (an Alternative approach):

Set X has only two digit numbers and the smallest number in set Y is 5.
So, the smallest number in the union of X and Y is definitely 5.

Let's look at the answers, starting with the largest:
If (E) were true, then the largest number would be 100, impossible.
If (D) were true, the largest would be 97. 97 isn't a multilpe of 5, but is it prime?
There is no easy way to answer this unfortuantely, we'll need to check by dividing 97 by all odd integers smaller than the root of 97 which is a bit less than 10.
97/3 = not an integer (9+7 = 16 is not divisible by 3)
97/5 = not an integer
97/7 = (70 + 27) = not an integer (because 28 is divisible by 7)
97/9 = not an integer.
Therefore 97 must be prime so the range is at least 97 - 5 = 92. Since this is our largest option, we'll pick it!

(D) is our answer.
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