Answer:
A
Step-by-step explanation:
Arithmetic sequences are those that have a common difference, as opposed to having a common ratio or no common difference at all.
Look at each answer choice:
A: Find the common difference by taking one term and subtracting the previous term from it.
-27 - (-20) = -27 + 20 = -7
-34 - (-27) = -34 + 27 = -7
If we keep doing this, we'll see that they all have a difference of -7, so this is an arithmetic sequence.
If we inspect the other three answer choices, we'll see that they do not have common differences.
Thus, A is the answer.
