Discuss the following problem. Influenza epidemics account for 250,000 to 500,000 deaths globally each year. These epidemics are markedly seasonal, occurring in temperate climates in the northern and southern hemispheres during their respective winters. By contrast, in the tropics, there is significant influenza activity year round, with a peak in the rainy season. Can you suggest some possible explanations for the patterns of influenza epidemics in temperate zones and the tropics?
a. Lack of medical facilities in tropical regions
b. Differences in immune system response between temperate and tropical populations
c. Variations in temperature and humidity between temperate and tropical regions
d. All of the above