September 1, 1939 — germany invades poland. september 27, 1940 — germany, japan, and the soviet union sign a pact stating they will not attack each other and will provide military assistance if attacked by a nation not already involved in the war. december 7, 1941 — japanese bombers destroy large portions of the u. s. navy fleet at pearl harbor. december 8, 1941 — the united states declares war on japan. december 11, 1941 — germany declares war on the united states. december 11, 1941 — the united states declares war on germany. based on the information in the timeline, which causal explanation for u. s. involvement in world war ii is most likely accurate? a. the united states became involved in world war ii to weaken the alliance of germany, japan, and the soviet union. b. the united states became involved in world war ii to protect european allies attacked by germany. c. the united states entered world war ii because japan attacked its navy. d. the united states entered world war ii because both japan and germany declared war on it.