What caused a hot war to break out in Korea

Stalin wanted to see Communism expand as long as he did not get involved in a 'hot war' with America. The trigger for the war was when, in 1950, Syngman Rhee boasted that he was going to attack North Korea. It was a good enough excuse – the North Koreans invaded South Korea. This started the actual fighting.

can someone me with this question:  

1) the end of the conflict between the north and the south didn’t just mark the end of a war; it marked the end of an entire way of life.” which statement best describes what this statement means?  

a) the southerners were no longer free and were controlled by the northern states.

b) the industrial economy in the north was not sustainable.

c) slavery became illegal, which changed completely the south’s labor force and the agricultural economy was destroyed.

d) the states decided to relinquish their independence and return to britain’s rule.