It's C.
Step-by-step explanation:
A geometric sequence has a common ratio (r) where each term after the first is obtained by multiplying the previous one by r.
Checking through the list we see it is C because:
Second term 15 = first term * 5 = 3(5) = 15.
Third term = 15*5 = 75,
4th term = 75*5 = 375 and so on.
The common ratio is 5.
Sequence C is a little different because it seems that we are dividing; yet to stay consistent with the theme of geometric sequences, we must think in terms of multiplication. We need to multiply by -1/2 to the first number to get the second number. This too works for any pair of consecutive numbers. The fourth number times -1/2 is the fifth number: -2 × -1/2 = 1.
- Martiinez <3