"Has the warning bell rang yet?" would be the best option from the list in terms of a participle. It often helps to say these types of sentences out loud to determine the right fit.
The answer is A. because saying it is the coolest car in the world is only an opinion.
Advent is most synonymous with “introduction”.
You can start the story off by the girl talking about why she is afraid of the dentist (dentist tools, dentists themselves, etc). Then she can talk about going to the dentist and how her experience was (good, bad etc). Then you can talk about how she faced her fear and if it was better or worse then she was expecting.
