Final answer:
The correct answer is option c. 50 million.
Step-by-step explanation:
The "Spanish Flu" epidemic following WW1 is estimated to have resulted in the deaths of between 50 million to 100 million people. It infected about 500 million worldwide, which was nearly a third of the world population at the time. This pandemic had a remarkable impact, possibly killing between 5% and 10% of the global population. In comparison with combat deaths, the flu caused more fatalities among soldiers than the battles of WW1. Its reach extended after the conflict with high mortality rates, underscoring the heightened virulence in comparison to standard flu epidemics.
The most lethal period of the pandemic occurred during the fall of 1918, coinciding with the Meuse-Argonne Offensive, critically affecting the American and German armies by weakening soldiers. Despite the intensive spread and high case fatality rate, no cure was found, and society had to rely on non-pharmaceutical interventions such as isolation and quarantine. This pandemic eventually faded in the early 1920s after four waves of worldwide infection.