Answer:
C
Explanation:
In a geometric sequence there is a common ratio. The common ratio is a number that you multiply each number of the sequence to get the next number.
A.
1, 2, 4, 6, 8, 10, ...
2/1 = 2
4/2 = 2
It looks like the common ratio is 2, but try the next division: 6/4 = 3/2
It is not 2, so there is no common ratio, and this is not a geometric sequence.
B.
-1, 0, 1, 2, 3, ...
0/-1 = 0
1/0 = undefined
There is no common ratio.
C.
-2/2 = -1
2/(-2) = -1
-2/2 = -1
The common ratio is -1.
This is a geometric sequence.
D.
3/5 = 3/5
1/3 = 1/3
No common ratio.
Answer: C