Correct Answer - Option 1 : (6 ∶ 13 ∶ 20)
The pattern follows here is;
First Number + 7 = Second Number
Second Number + 7 = Third Number
In (23 ∶ 30 ∶ 37);
23 + 7 = 30
30 + 7 = 37
Similarly;
In (6 ∶ 13 ∶ 20)
6 + 7 = 13
13 + 7 = 20
Hence, (6 ∶ 13 ∶ 20) is the correct answer.