Although Japan Has One of the World's Highest Life Expectancies,it

Although Japan has one of the world's highest life expectancies,it has experienced a net loss of population for many years,the result of declining birth rates and very low immigration rates.However,the population rose in both 2008 and 2009,largely due to Japanese citizens abroad returning home.This data was collected by a:

A) demographer.
B) social ecologist.
C) environmental sociologist.
D) nongovernmental organization.