Option: C
Solution: The relationship between 1st & Second group is x: (x³ – x²). So the correct answer is option (c).

Option: b
Solution: In this set, all the numbers have their digit sum as 7.
Out of these options, answer will be 205 as this is the only option with digit sum 7.
Hence, the correct answer is option (b).

Option: d
Solution: In all the numbers, (1st digit + 3rd digit) - middle digit = 10.
Thus, the correct answer is option (d).

Option: a
Solution: The 1st, 2nd and 3rd letters of the 1st group are moved 1, 3 and 5 steps forward respectively to obtain the corresponding letters of the 2nd group. So, the correct answer is option (a).

Option: d
Solution: The order of the letters of the 1st group is reversed & each letter is moved 2 step backward to obtain the corresponding letters of the 2nd group. So, the correct answer is option (d).

Option: d
Solution: The first three letters and the last three letters of the first group are written in a reverse order to obtain the second group. So, the correct answer is option (d).

Option: a
Solution: The relationship between 1st & Second group is x : (x³ – x²) . So the correct answer is option (a).

Option: a
Solution: In all the numbers, the middle digit is the average of first and third digit.
So the correct answer is option (a).

Option: d
Solution: In all the numbers, (1st digit + 3rd digit) - middle digit = 9.
Thus, the correct answer is option (d).

Option: a
Solution: The 1st, 2nd and 3rd letters of the 1st group are moved 1, 3 and 5 steps forward respectively to obtain the corresponding letters of the 2nd group. So, the correct answer is option (a).