Why is - 12.3,-9.7,-7.1,-4.5 an arithmetic sequence

Step-by-step explanation:

arithmetic sequence is a sequence, if difference between any two consecutive terms is same for all.

difference of first two terms: - 9.7 - (-12.3) = 2.6

difference of third and seconf term: - 7.1 - (-9.7) = 2.6

and so o, as difference between any of the consecutive terms is same i. e 2.6, the given sequence is arithmetic.