Answer: A cause-and-effect relationship is signaled by the words "But since."
Step-by-step explanation:
A cause-effect relationship refers to a relationship whereby one event will lead to the cause of another event. For the effect to occur, the cause must have taken place.
The statement that best describes the relationship of ideas in this text is that a cause-and-effect relationship is signaled by the words "But since." It explains how the 3M's policy had and effect on something else.