Need help ASAP

1.) List a few reasons why a beaver is an example of a keystone species.

2.) In architecture, a keystone is the
stone at the center of an arch that holds the arch together. How does this
definition relate to a keystone species?

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

The body of water found at number 4 on the map above is the

Which is the graph of the piecewise function f(x)? f(x) = image for option 1 image for option 2 image for option 3 image for option 4