Please choose the correct answer to the question: In 1987, a supernova was detected in the Large Magellanic Cloud galaxy, which is approximately 169,000 light years from Earth. Which event produces a supernova?

Answer1: the explosion of a massive star Answer2: the birth of a main-sequence star Answer3: the collapse of a medium-sized star Answer4: the collision of one star with another

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