Select the option in which the numbers are not related

Solution

The logic followed here is as follows: Each number in the given triplets is the square of three consecutive natural numbers. For (11², 12², 13²) = (121, 144, 169) For option 'a': (19², 20², 21²) = (361, 400, 441) For option 'b': (3², 4², 5²) = (9, 16, 25) For option 'c': (17², 18², 19²) = (289, 324, 361) For option 'd': (7², 8², 9²) = (49, 64, 81) In option 'd', the third number given is 121 (11²), which is not the square of the consecutive number 9.