Explanation:
Given the importance of oxygen for animals, researchers suspected that a sudden increase in the gas to near-modern levels in the ocean could have spurred the Cambrian explosion. ... This supported the idea of oxygen as a key trigger for the evolutionary explosion.
"we hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable rights." last two phrases talk about how all men created equal.
Answer:
U-shaped valleys, hanging valleys, cirques, horns, and aretes
Explanation:
C. Economic opportunity.
They were looking for work or wanted to start small businesses.