Can you check the following?

Experiment A: Four groups of rats are first massed and then fed identical diets except for the amount of vitamin A they receive. Each group gets a different amount. After three weeks on the diet, the rats’ masses are measured again to see if there has been a decrease.
57. What is the manipulated (independent) variable?
Ans: vitamin A

58. What is the responding (dependent) variable?
Ans: mass

59. What is the controlled variable?
Ans: diet

Right on all counts.

To determine the manipulated (independent) variable in this experiment, you should identify the factor that the researchers intentionally change or manipulate. In this case, the manipulated variable is the amount of vitamin A that each group of rats receives. Each group is given a different amount of vitamin A.

To determine the responding (dependent) variable, focus on the factor that the researchers measure or observe in response to the changes made in the experiment. In this case, the responding variable is the mass of the rats. The researchers measure the mass of the rats before the experiment and after three weeks on the diet to see if there has been a decrease.

The controlled variable refers to the factor that remains constant throughout the experiment, ensuring that it does not influence the results. In this case, the controlled variable is the diet. All groups of rats are fed identical diets except for the amount of vitamin A they receive. The controlled diet helps isolate the effect of the manipulated variable (vitamin A) on the responding variable (mass).