(a) is the correct option
Step-by-step explanation:
Yield of tomatoes is a dependent variable
- The dependent variable is something that is observable and measurable, here in this case yield of tomatoes can be calculated and measured depending on the type or concentration of fertilizer used
- The independent variable, also known as the experimental treatment is the difference or change in the experimental conditions that is chosen, here in this case it is the concentration or type of fertilizer
- To ensure that only the independent variable is affecting the dependent variable, all the other factors acting upon the test situation must be kept constant, these factors that must be kept the same are called the controlled variables, or constant variables
- Here in this case amount of water, exposure to sunlight and type of seedlings is kept same