In a new trial to test the effectiveness for a new type of medicine, why is it necessary for one group to receive a placebo?

Apower company wants to build a power plant on the severn river in france. read the following details about the plant and then answer the question that follows: the plant will -provide 10% of the country's energy needs - has a tide amplitude of 11 meters - will be built across a narrow inlet (15 kilometers) -could reduce coal emissions in the area by 3 percent by replacing fossil fuel power - will alter the feeding grounds of local birds. it is unknown how these birds would adapt. fish in the inlet are able to pass through the turbines. occasionally, however, they can get trapped and die do you think this tidal power plant should be built? why or why not?