Which of the following show a geometric series? Select all that apply.

2 + 3 + 4.5 + 6.75 + …

2 + 2.5 + 3 + 3.5 + …

6 + 7 + 9 + 12 + …

4 + 8 + 16 + 20 + …

8 + 4 + 2 + 1 + …