What is the variable do plants grow taller with fertilizer?

The variable that affects whether plants grow taller with fertilizer is the amount and type of fertilizer applied. Fertilizers provide essential nutrients, such as nitrogen, phosphorus, and potassium, which can enhance plant growth and development. By controlling and varying these factors, researchers can observe how different fertilizer compositions influence the height and overall health of the plants. Thus, the growth response serves as a dependent variable in experiments assessing fertilizer effectiveness.