Send help please.

1. Which of the following is an arithmetic sequence?
a. ½, 1,2,4...
b. ³/⁷, 13/14, 10/7...
c. 3, 15/18, 15/11...
d. ⅘, ⅕, ¹/20,...

2. Which of the following is an arithmetic sequence?
a. 2√2, 5√2, 8√2, 11√2,...
b. 6/11, 6/17, 6/23, 6/29
c. 6, -18, 54, -162,...
d. ⅘, ⅕, 1/20,...

Thank you ​