Below are given two sets of numbers. In each set of numbers, a certain mathematical operation on first number results in the second number. Similarly, certain mathematical operation on second number results in the third number and so on. Which of the given options follows the same set of operations as that followed in the question? (NOTE – A two/three digit number cannot be broken into individual digits for operations; e.g., if 37 is followed by 10, the operation cannot be 3+7 as a two digit number cannot be broken into individual digits.) 2 – 6 – 12 – 20 ; 3 – 7 – 13 – 21