Over the past 30 years in the United States, there has been a strong negative correlation between

Question:

Over the past 30 years in the United States, there has been a strong negative correlation between the number of infant deaths at birth and the number of people over age 65.
(a) Is the fact that people are living longer causing a decrease in infant mortalities at birth?
(b) What lurking variables might be causing the change in one or both of the variables? Explain.