Answer:
The option that helps a reader visualize a sequence of events in this passage is:
b. “...form when cold air moves over warm water.”
Step-by-step explanation:
The reasons for this answer are two-. The first one is that this sentence uses "when" a temporary connector that allows us to understand the origin of the event on the matter. Also, the "a" option is a complementary sentence that keeps following the order established by the "b" option, but not starts another order of sequence. It is the same one.