Transitional Phrases Such as "Next," "Meanwhile," "Finally," and "Simultaneously

Transitional phrases such as "next," "meanwhile," "finally," and "simultaneously"

A) only clutter up a set of instructions.
B) are totally unnecessary because instructions tend to be presented in numbered lists.
C) provide useful bridges that help readers understand the step-by-step sequence.
D) don't provide a useful function but they don't do any harm, either.