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.

[Q]: Question: When we pack a fewer things into a box it becomes 
 Answer: less dense
[A]: The more tightly packed the particles inside the material are, the more dense we say they are.


[Q]: Question: An increase in birth rates indicates a/an _____ in the food supply. 
 Answer: increase
[A]: Low food supply or a lack of space can lower birth rates, increase death rates, or lead to emigration.


[Q]: Question: When people learned how to farm the population 
 Answer: increased
[A]:
More recently, the death rate has fallen because of the availability of more food and medical advances.