Which of the following statements are true about the inciden…

Which of the following statements are true about the incidence of asthma?1. The prevalence has increased over the past 20 years in the United States.2. The mortality has decreased over the past 20 years in the United States.3. Researchers have determined the causes of asthma and are working on a vaccine.4. Diagnosis of asthma is done in a physician’s office following a physical exam.