After the breakup of the soviet union many former soviet nations came together and organized
a. the union of soviet socialist republics
b. the commonwealth of independent states
c. the european union
d. nato

After the breakup of the Soviet Union many former Soviet nations came together and organized the Commonwealth of Independent States. The correct option among all the options given in the question is option "b". This organization was formed on 8th of December in the year 1991. It is a loosely formed association between the countries that broke up from the former Soviet Union.