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 /deleting /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)

(21, 3 , 15)

(49, 7, 35)

To find the correct set, let us analyze the mathematical relationship between the numbers in the given sets. Let the three numbers in each set be represented as ($A$, $B$, $C$).

Let us analyze the first given set: (21, 3, 15)
Here, $A=21$, $B=3$, and $C=15$.
If we look at the relationship between the first number and the second number:
$21=3\times 7$ (i.e., $A=7\times B$)
If we look at the relationship between the third number and the second number:
$15=3\times 5$ (i.e., $C=5\times B$)

Let us verify this relationship with the second given set: (49, 7, 35)
Here, $A=49$, $B=7$, and $C=35$.
Applying the same logic:
$49=7\times 7$ (i.e., $A=7\times B$)
$35=7\times 5$ (i.e., $C=5\times B$)
The pattern is consistent across both sets.

Now, let us test the options to find the set that follows the same rule:
Check the option (84, 12, 60):
Here, $A=84$, $B=12$, and $C=60$.
Let's verify:
$12\times 7=84$ (satisfies $A=7\times B$)
$12\times 5=60$ (satisfies $C=5\times B$)

Since both conditions are satisfied, the numbers in the set (84, 12, 60) are related in the same way as the numbers of the given sets.