Answer:
The correct answer is option D. they were part of the control group.
Explanation:
A control group is a group of subjects different from the other test subject as they did not get the independent variable's effect on them and separated from the rest of the experiment. This group of subjects is used to rule out any other explanation of the effect of the independent variable.
In this experiment, subjects that received a placebo injection are the control group as they did not expose to the mutated virus and there are the presence of antibodies in the blood.
Both types of rocks form under high pressure, but metamorphic also requires heat.
When the pancreas is stimulated it releases Insulin. insulin helps store sugar in throughout the body.
B, dam removal allows streams to connect the mountains to the ocean.
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