Why did Japan attack China in 1937, launching the Second Sino-Japanese War?

to spread communism to other parts of Asia
to secure natural resources for its growing economy and military
to secure a buffer area against a potential Soviet attack on Japan
to retaliate after China’s attack on Japanese port cities

it is  A.  to secure natural resources for its growing economy and military

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.