A scientist formulates the following hypothesis: If plants of the same species are grown under the same conditions, the amount of fertilizer the plants
receive will affect their growth rate. Which variable will be a responding
variable in the experiment designed to test this hypothesis?

Growth rate

Explanation:

The responding variable, also known as the DEPENDENT VARIABLE, is the variable that responds to changes or manipulations made to another variable (independent or manipulable variable) in the experiment. It is the measured variable of an experiment.

According to the hypothesis provided for this investigation, the scientist wants to determine if the amount of fertilizer plants of the same species receive will affect their growth rate when planted in the same condition. This shows that the independent variable is the amount of fertilizer to be used while the RESPONDING VARIABLE OR DEPENDENT VARIABLE is the GROWTH RATE OF THE PLANTS because it responds to the amount of fertilizer.