Solution:The pattern followed here is :{(1st number ร 2) - 1} = 2nd number & {(2nd number ร 2) - 2} = 3rd number
(19, 37, 72) โ {(19 ร 2) - 1} = 37 & {(37 ร 2) - 2} = 72
(15, 29, 56) โ {(15 ร 2) - 1} = 29 & {(29 ร 2) - 2} = 56
Similarly,
(11, 21, 40) โ {(11 ร 2) - 1} = 21 & {(21 ร 2) - 2} = 40
Hence, "(11, 21, 40)" is the correct answer.