instruction:
In this task, you are given a question and answer for that. The answer will fill in the blank or will complete the unfinished question. Your task is to provide an explanation based on the given question or fill-in-the-blank statement, and answer.
question:
Question: Eileen studied two identically sized populations of women, one in Springfield where the women were in their 50s and one in Mayfield where the women were in their 30s. The population with a lower incidence of breast cancer was 
 Answer: Mayfield group.
answer:
Breast cancer is rare in teens. It becomes more common as women get older.


question:
Question: If Jim lowers the temperature of water in his bathtub, what happens to the density of the water? 
 Answer: increases
answer:
Water becomes more dense when it is colder and when it has more salt.


question:
Question: Air pressure is higher in the 
 Answer: valleys.
answer:

Air pressure is less at higher elevations.