Please choose the correct answer to the question: Vehicle exhaust contains a form of pollution called particulate matter. Technologies are being developed to reduce the amount of particulate matter in exhaust. A vehicle that produces less particulate matter would have the greatest impact on which aspect of human health?

Answer1: heart health Answer2: respiratory health Answer3: the rate of birth defects Answer4: weight and physical fitness

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