Correct option is B
In this question following logic is followed -
(1st ÷ 4)2 – (2nd ÷ 6)2 = 3rd Number
36, 24, 65 → (36÷ 4)2 – (24 ÷ 6)2 = 92 - 42 = 81 – 16 = 65
40, 54, 19 → (40÷ 4)2 – (54 ÷ 6)2 = 102 - 92 = 100 – 81 = 19
Similarly,
20, 18, 16 → (20÷ 4)2 – (18 ÷ 6)2 = 52 - 32 = 25 – 9 = 16
Therefore, the correct answer is (b).