Please choose the correct answer to the question: Tom noticed it was getting gloomy outside at only two in the afternoon. Which of these might be the cause?

Answer1: the witch at the top of the hill has placed a spell on the town Answer2: a warm front has moved overhead Answer3: a funeral is about to start at the church across the street Answer4: the earth is moving through a dark area of space

Answer format: answer1/answer2/answer3/answer4
Answer: answer2