The development of the hydrogen bomb by the united states and the u.s.s.r. was one result of
a. the cold war rivalry between the two nations in the 1950s.
b. the world war ii alliance between the two nations in the 1940s.
c. battles between the two nations during the vietnam war of the 1960s.
d. disagreements between the two nations during the afghan war of the 1980s.