Which of these is a geometric sequence?

A geometric sequence deals with multiplying...u have to multiply by a common number to get the next number

1/4 * 2 = 1/2
1/2 * 2 = 1
1 * 2 = 2
2 * 2 = 4

so ur geometric sequence is : 1/4, 1/2, 1, 2, 4...with a common ratio of 2