From late 1941 into early 1942, World War II in the Pacific experienced:
1.(i am not sure) a string of American victories that put Japan on the defensive
2.(wrong) the Japanese invasion and capture of Australia
3.(wrong) the Japanese on the Philippines surrender to General Douglas MacArthur
4.(possible) a succession of Japanese victories that saw numerous Allied outposts fall
5.(wrong) China finally surrendering to Japan
You're right -- it's either 1 or 4.
I see 4 as a more possible answer.
Because in the timeline there is no mention of AMerican victories at the time.