Answer: b. the height of the plant.
In an experimental set up an independent variable is the one which can be manipulated or change to observe the effects of such changes or manipulation on dependent variable. For example, plant growth is a dependent variable because it is dependent on independent variables such as amount of sunlight available, amount of fertilizers and water provided.
In this experiment, it is to be determined that how the amount of water given to a plant affects its growth. Here, water is an independent variable which can be change in the experiment and the affect of change can be observed on plant growth which is a dependent variable. A height represents the growth of the plant therefore, height of the plant is the dependent variable.
