A dependable state of peace between two populaces sharing the same region does not imply that the average life expectancy of humans will remain constant. Epidemics and natural disasters and unstable weather particularly in response to the 'greenhouse effect' and the subsequent cooling and warming of effected regions generate oscillations in mean life expectancy and lead populations to increase or decrease their averaged age.

Question: Average life expectancy decreases due to the cooling of some regions.
Options:
A. true, B. false, C. uncertain
Answer: "C"