A researcher is collecting data to analyze the rate of chickenpox cases in the U.S. per year, as well as birth rate each year. She noticed that as the birth rate increasing per year, the rate of chickenpox among babies increases. The reverse is also true. Which of the following statements are true? These two variables appear to be highly correlated Increased measles rate is caused by an increase in the birth rate None of these are true Increased birth rate is caused by an increase in the measles rate