<h2>A) Directly changed by the experimenter.</h2><h2 /><h2>Explanation:</h2><h2 />
In mathematical modeling, analytical modeling and experimental sciences, the values of dependent variables depend on the values of independent variables. The dependent variables describe the output or outcome whose change is being examined. An independent variable seldom named an experimental or predictor variable, is a variable that is being formed in an experiment in order to inspect the impact on a dependent variable, sometimes described as an outcome variable.
People with O+ blood cannot donate their blood to negative blood types, while people with O- blood can donate to any blood type. This makes them the "universal donor." However, they can only receive O- blood.
