The transition word that signals cause-and-effect in the given options is "as a result."
The transition word that signals cause-and-effect is "as a result". To determine this, you can look for keywords or phrases that suggest a cause and its resulting effect. In this case, the phrase "as a result" directly indicates that there is a cause-and-effect relationship between two ideas or events. The other transition words and phrases ("however", "first", and "finally") do not express cause-and-effect relationships, but rather indicate contrast, sequence, or conclusion.
