Final answer:
The period between 1965 and 1980 experienced the highest annual population increase with a growth rate of 2%, which is not matched by the given options or the projected rates for 2040-2050.
Step-by-step explanation:
The decade with the highest annual population increase is 1965-1980, when the world population grew at an annual rate of 2%. This rate suggests a population doubling time of approximately 36 years. During this time, rapid population growth was prevalent, as indicated by later historical data showing it took just 24 years to add two billion people between 1975 and 1999. However, for the future projection of 2040-2050, the population growth is expected to slow down compared to prior decades, even though the numbers are predicted to rise to 9.7 billion by 2050 as per United Nations projections. Thus, the highest annual population increase did not occur in the 1980s, 1990s, 2000s, or is projected for the 2040s, but rather during the period between 1965 and 1980.