Answer: D. Plant D
Step-by-step explanation:
In an experimental setup an independent variable is the one which can be changed or manipulated in an experimental. The changes occurring in the independent variables likely to affect the outcomes of the dependent variable. The dependent variable cannot be manipulated but the changes occurring in the dependent variable occurs due to the changes in the independent variable. The control group or variable is the one which is used as a standard in an experiment setup to compare the changes occurring in the tested sample with respect to the application of the manipulated variables.
According to the given situation, the music is the independent variable over which the growth of the plant is dependent upon. Hence, the growth of the plant is dependent variable. The control group is the Plant D which does not listen to any music at all. This is kept in the experiment to determine weather growth of plant is dependent upon music or natural conditions such as soil, sunlight and water are sufficient.