Answer: a. the amount of water
Independent variable can be defined as a variable which can be changed or manipulated in an experimental set up to record and observe it's effect on the dependent variable. A dependent variable is a variable which is dependent on the independent variable. The outcome of the dependent variable is the result of the experiment. A controlled variable is a variable which does not change in a reaction, and kept as a constant.
1. Here, in the given situation, the amount of water is an independent variable, as it can be manipulated or change in an experiment and it's impact on the growth of plant, which is a dependent variable needs to be observed.
2.Here, in the given, situation, the type of plant is a constant or control variable, as it is irrespective of the changes that occur in the dependent variable with respect to the independent variable.
