Aclimatologist removes an ice core sample from the antarctic. she finds volcanic ash at the bottom of the core, followed by increasing amounts of dissolved oxygen as she goes to the top of the core sample. which of the following can be concluded based on this information?

after a volcano erupted, all plants in the surrounding area died.
a volcano erupted due to the increasing amount of oxygen in the atmosphere.
as the amount of oxygen in the atmosphere decreased, a volcano erupted.
a volcano erupted, followed by a period of increased oxygen in the atmosphere.

Dr. robbins wants to know if there are different opinions regarding the value of public school education between native americans who have at least one relative who attended indian boarding school and native americans who have no family experience with indian boarding school. dr. robbins contacts 35 native american participants in each group. he wants each group to include younger as well as older adults, and a mix of male and female participants. he asks each person to complete a survey about their attitudes toward public education. the design of this study is:

The health care system in is referred to as a singleminus−payer health care system, and is a system in which the government provides national health insurance to all residents.

The federal reserve is responsible for overseeing all a. income tax refunds b. changes in tax policies c. government spending d. depository institutions