Match the sequence (term) with the correct type of sequence (definition).
1. 128, 32, 8, 2, ...
2. 1, 3, 9, 27, ...
3. 5, 10, 15, 20, ...
4. 20, 17, 14, 11, ...
a. Arithmetic, common difference is 3
b. Geometric, common ratio is 0.25
c. Geometric, common ratio is 3
d. Arithmetic, common difference is 5