Astudent designs an experiment where she will add varying amounts of sugar to a chemical reaction and then measure the mass of the chemicals produced during each reaction. the independent variable in this experiment is:
the amount of sugar
the mass of the chemical produced
the temperature of the reaction
the type of chemical reaction

The correct answer is A. The amount of sugar

Explanation:

In experiments variables or factors that can be measured are often classified as dependent or independent. In this way, dependent variables include the main factor or factors that are being studied while the independent variable is the factor controlled by the scientists and therefore the factor that is believed affects the dependent variable. This means, in the case presented, the amount of sugar is the independent variable as this is the factor the student is manipulating to prove if it influences the mass of chemicals.

answer: the dogs need to shift their focus to human scent.

its because the dogs being trained are for search and rescue thus they need to be able to track humans and their specific scent