Well for solving arithmetic sequences you have to add the numbers like for example if you had 2,4,6,8 The Common ratio would be 2 because you're constantly adding 2. Now for a geometric sequence it's a little different instead of adding the numbers you use multiplication to solve those ones so if the numbers were 4,16,64,256 the common ratio would be 4.
Now here comes the answers. For the matching :)
1. B Arithmetic, common difference is 2.
2. C Arithmetic, common difference is -4.
3. D Geometric, common ratio is 2.
4. A Geometric, common ratio is 0.5.
Hope This Helps You! Have A Wonderful Day. :)