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 its constituent digits. E.g. 13 – Operations on 13 such as adding / subtracting / multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is NOT allowed)
(4, 6, 9)
(25, 10, 4)

Correct option is C

Logic - second number = √first number× √third number

Set (4, 6, 9): 
√4 = 2
√9 = 3
2 × 3 = 6 Matches
Set (25, 10, 4):
√25 = 5
√4 = 2
5 × 2 = 10 Matches
So the logic works.
Step 2: Check the options
(A) (23, 3, 32)
√23 ≈ 4.795
√32 ≈ 5.657
Product ≈ 27.1 ≠ 3
(B) (45, 20, 19)
√45 ≈ 6.708
√19 ≈ 4.359
Product ≈ 29.3 ≠ 20
(C) (6, 36, 216)
√6 ≈ 2.449
√216 ≈ 14.697
Product ≈ 36 Matches
(D) (98, 7, 89)
√98 ≈ 9.899
√89 ≈ 9.434
Product ≈ 93.4 ≠ 7
 Correct Answer:
(c) (6, 36, 216)

Alternative method: