Which one of the following is an arithmetic sequence? a. −2, 1, 4, 7, 10, . . b. 2, 3, 5, 7, 11, 13, 17, . . c. 5, 0, −1, −3, −7, . . d. 35, .5, .85, 1.1, 1.22, . .

Arithmetic sequences are sequences who have the same difference every where. for example 0,2,4,6,8 is an arithmetic sequence since the difference between any two terms is equal to 2
we express this mathematically by saying let q be the common difference let a(n) be the nth term of a sequence than the sequence is only arithmetic if and only if for (1st)to(n-1th term) the difference  a(n+1)=a(n)+q and a(n)=q*n
so let us check the choices
A)-2,1,4,7,10 is arithmetic since the common difference is 3
B)2,3,5,7,11,13,17 is not arithmetic since there is no common difference
c)5,0,-1,-3,-7 is not arithmetic since there is no common difference
D)0.35,0.5,0.85,1.1,1.22 isn't arithmetic since there is no common difference