In recent years, a decline in economic productivity has occurred in some countries as a result a. nationalism. b. the black death. c. the spanish flu. d. the aids pandemic.

Option D.

The AIDS has become the global pandemic in recent years.

Explanation:

AIDS is the disease caused by HIV retro virus. It suppresses the immune system and causes gradual sickening of the host and finally death.  The Black Death or Plague is the disease that affects humans and mammals. It is caused by bacteria and human suffer when bitten by rodent flea or handling of animals infected. It was one of the worse pandemics in the 14th century in Europe.  The Spanish flu was the disease that became pandemic in 1918. It is caused by virus H1N1 influenza virus, similar to the virus of birdflu.  

To have a bunch of countries to team up, and communicate not let the communist break them apart and take over the world