The graph shows data collected near the Mauna Loa volcano in Hawaii from 1955 to 2015. The data includes atmospheric CO2 levels, seawater CO2 concentrations, and seawater pH readings. If the current trend continues, the seawater near Mauna Loa will likely become due to the changing concentration of in the water.

"choosing is refusing" means individuals face an opportunity cost with each decision they make. economists state that every decision involves trade-offs. opportunity cost is the least desirable alternative given up as a result of a decision.

explanation:

may i ask what challenges?

the old way of life was represented by superstition, an angry god, and absolute submission to authority. the thinkers of the age of reason ushered in a new way of thinking. this new way championed the accomplishments of humankind. individuals did not have to accept despair. science and reason could bring happiness and progress. kings did not rule by divine right. they had an obligation to their subjects. europeans pondered the implications for nearly a century. americans put them into practice first.