Arithmetic sequences are defined by a common difference between the numbers that’s both constant and consecutive.
To break it down:
The first option is {-1, 3, -3, -1}, which appears to be alternating, and there is more than 1 difference between the n term values. That is:
-1 to 3 = increase of 4 3 to -3 = decrease of 6 -3 to -1 = increase of 2
Therefore does not follow the definition of an arithmetic sequence.
The second option (the answer) {2, -2, -6, -10} is arithmetic, as it consistently and thus consecutively decreases by 4.
Finally, the last two sequences have the same issue with their pattern, {3, 6, 9, 15} and {4, 14, 24, 32}. In which they stay constant for the first three n terms, but suddenly change in value on the 4th n term. Therefore, they are not arithmetic.
