Please choose the correct answer to the question: In some national parks, controlled fires are maintained by firefighters. Which of these is one of the major reasons for using controlled burns to maintain certain ecosystems?

Answer1: to give nonnative plants a chance to colonize the region Answer2: to prevent the spread of pests that cause damage to plants Answer3: to replace matured plants with saplings of the same species Answer4: to rid the forest floor of accumulated deadwood and brush

Answer format: answer1/answer2/answer3/answer4