Which Statement Best Describes the Relationship Between the Environment and Health

Which statement best describes the relationship between the environment and health?

A) Because of the large number of variables involved,the relationship between environment and health cannot be researched
B) Because the environment has such long-term effects on health,research findings are not yet available
C) Research shows that a healthy environment has limited impact on one's health
D) Research shows that a healthy environment increases quality of life and years of healthy living.