Answer:
4 + 12 + 36 + ...
Step-by-step explanation:
4, 12, 36, ... is a geometric sequence, it has a common ratio of
When we add the terms of a geometric sequence we get a geometric series.
4+12+36+ ... is a geometric series, it has a common ratio of
4 + 12 + 20 + ... is not a geometric series because it has no common ratio
The second choice is correct