Which statements can be inferred from the Paleozoic era time scale? There was volcanic activity during the Paleozoic era. Dinosaurs existed in the middle part of the Paleozoic era. Marine organisms existed in the early part of the Paleozoic era. Ammonites existed before the trilobites did during the Paleozoic era. Erosion and deposition were processes that occurred during the Paleozoic era.

Researchers randomly divide participants into groups. each group takes a different amount of omega-3 fatty acid supplements daily for a month. one group receives a placebo. the researchers measure the impact on cholesterol levels in the blood. what is the purpose of random assignment in this experiment? a, to produce treatment groups with similar characteristics b, to ensure that all people with high cholesterol have an equal chance of being selected for the study c, to increase the accuracy of the research results and prevent skewness in the data

Why are scientists concerned about the depletion of the ozone levels in the stratosphere?

Which greenhouse gas is emitted when burn fossil fuels for energy? a.nitrogen b.oxygen c.carbon dioxide d.helium