Read the short story and answer the question. The legendary explorer, Amelia, began her journey to the Amazon rainforest on March 1st, 1920. She spent six months documenting new species of plants and animals. On September 15th, she discovered an ancient, forgotten city. Her return trip started on October 1st, and she arrived back in her home country on November 20th, bringing incredible stories and findings. Which of the following events happened *before* Amelia discovered the ancient city?
A) Her return trip started.