Someone please help asap! I will give brainliest if right!

C. 1 - IV (Independent Variable), 2 - constant, 3 - DV (Dependent Variable)

Explanation:

In science, an independent variable in an experiment is defined as a variable that is changed in order to see how it affects another variable. By analyzing the chart one can see that the pH is changed to see how the height of the plant changes. Thus, the pH is an independent variable.

A constant variable in an experiment is defined as a variable that remains constant throughout the entire experiment so that the researcher does not get conflicting results due to factors that were not relevant to the experiment. As the temperature indicated in the chart remains at 23 degrees Celsius for each and every plant, it is a constant variable.

A dependent variable in an experiment is defined as a variable that is the main focus of the experiment, where the researcher changes certain factors in order to observe how the variable changes. As the experiment features the researcher changing the pH value in order to determine how the height changes, the height is the dependent variable.

Thus, the answer is C.

it creates acid rain