What is the purpose of the cause-and-effect signal word “therefore”?

A) It signals to the reader that there is more information about the research surrounding how much time should be spent at recess.
B) It signals to the reader that the writer is going to offer an opposing view about how much time should be spent at recess.
C) It signals to the reader that the person has come to a decision about how much time should be spent at recess.
D) It signals to the reader that the idea of how much time should be spent at recess is debated due to different research findings.