Hmm, there were several triggering events that promoted westward expansion of the United States. Victory in war over Mexico (1848) gave the US new lands in the west. A treaty with Britain (also in 1848) gave the US sole possession of some formerly disputed Oregon territory lands also. Plus, in 1848, gold was discovered in California (land newly in US possession after that Mexican war treaty), so that prodded westward expansion too. Perhaps those are the initial "turning points" you're looking for. The completion of the Transcontinental Railroad in 1869 sure helped the process as it was underway, as well.
Answer:
A, B, B, C, D.
Explanation:
I am sorry if it is incorrect, I hope this finds you well!
<span>It was a Portuguese explorer named Vasco de Gama</span>
B. it allowed humans to continue to treat everyone in society equally
