Select the set in which the numbers are related in the same way as are the numbers of the following sets.
(NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into their constituent digits. E.g. 13 – Operations on 13 such as adding to/subtracting from/multiplying with 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed.)
(3, 15, 5)
(7, 35, 5) ​​

Given: 

(3, 15, 5)
(7, 35, 5) ​​

Logic: 1st number × 3rd number = 2nd number

For, (3, 15, 5)

3 × 5 = 15

For, (7, 35, 5)

7 × 5 = 35
Now, we check each options.
​Option (a): (9, 27, 9)

9 × 9 $$\ne$$​ 27
​Option (b): ​(5, 30, 5)

5 × 5 $$\ne$$​30
​Option (c): ​(6, 24, 6)

6 × 6 $$\ne$$​ 24
​Option (d): ​(8, 40, 5)

8 × 5 = 40
Thus, correct option is (d).