What was Edwin Hubble's contribution to the field of astronomy? A. He discovered variable stars.

B. He proved that the heliocentric model accurately described our solar system.

C. He found a relationship between the period luminosity and distance of stars.

D. He proved that the universe is finite.

E. He discovered that the universe was expanding.

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 picture shows a fishing technique called trawling. how might trawling affect marine biodiversity

Plz ! for many generations farmers in north america have been choosing to cross corn plants with large ears of corn each year this results in the new generation of plants also growing large ears of corn. what is the technique called? a. selective breeding. b. natural selection. c. mitosis. d. asexual budding.