Which of the following reasons makes the second world war very significant?
a. It marked the beginning of the Cold War.
b. The Allied Forces defeated the Axis Powers.
c. The atomic bomb was used for the first time causing unprecedented damage.
d. The US and Russia became the two leading superpowers.

a,b and c only

The end of the second world war marked the beginning of the Cold War. It ended with the dropping of the atomic bomb on the two cities of Hiroshima and Nagasaki in Japan by the US. The allied forced defeated the Axis Powers and thereafter the US and the USSR became the two leading superpowers.