Which of the following is a geometric sequence? 0, 2, 6, 12, 72, . . 1/2,2/3,3/4,4/5,5/6. . 4, 9, 14, 19, 24, . . 1, 3, 9, 27, 81, . .

What sets apart a geometric series is the common ratio between consecutive terms, Thus the geometric series from the list of series given include:
1,3,9,27,81,...
this is because it has a common ratio of:
3/1=9/3=27/9=81/27=3
Hence the answer is:
1, 3, 9, 27, 81, . . .