The invasion of Poland is regarded as the catalyst that began... * The Great War
World War II (2)
The American Revolution
The Civil War

b) World War II

world war 2

Explanation:

answer: what was the us involvement in ww1? although the u.s. tried to remain neutral when ww1 broke out, it finally joined on april 6, 1917 after declaring war on germany. the reason for america to become involved in ww1 was germany's unrestricted submarine warfare, which had already sunk several american merchant ships.

explanation:

i think the answer is b.