Correct Answer - Option 3 : 217
The given series are -
3, 28, 4, 65, 5, 126, 6, ?
Cube of the first number and add one then we get second number-
33 + 1 = 27 + 1 = 28
Cube of the third number and add one then we get fourth number-
43 + 1 = 64 + 1 = 65
Cube of the fifth number and add one then we get sixth number-
53 + 1 = 125 + 1 = 126
Similarly,
Cube of the seventh number and add one then we get eight number-
63 + 1 = 216 + 1 = 217
Hence, "217" is the correct answer.