Answer:
b. Sequences
Step-by-step explanation:
The following are progressions:
b. Sequences
We have two sequences - arithmetic progression and geometric progression.
A sequence is an arithmetic sequence if the two consecutive numbers have a common difference.
A sequence is a geometric sequence, if the ratio of two consecutive numbers is common.
The sum of the terms of a sequence is called a series. So, in a rather informal way, this can also be considered.