Select the pair from among the given options that is analogous to the given pair.

10 : 999

2 : 7

(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 1and 3 and then performing mathematical operations on 1 and 3 is not allowed.)

10 and 999 → 10³ = 1000,

1000 - 1 = 999
2 and 7 → 2³ = 8,

8 - 1 = 7 

Logic: 1stnumber³ - 1 = 2nd 

A) 6 and 215
6³ = 216
215 = 216 - 1 → fits the pattern

B) 4 and 65
4³ = 64
65 ≠ 64 - 1

C) 5 and 128
5³ = 125
128 ≠ 125 - 1

D) 8 and 315
8³ = 512
315 ≠ 512 - 1

Thus, correct option is (a).