Hi there!
(Because this question has been asked before, I will be recycling my previous answer to answer your question.)
In the experiment we can identify the variables to determine if the result of the experiment is sound.
Dependent variable - Growth of plants
Independent variable(s) - Medium of watering, being talked to and not talked to
In an experiment you want to have 1 independent variable to determine if that 1 variable is influencing the dependent variable. Because there are two independent variables in this experiment, it is impossible to tell which one caused the plants that were talked to to grow more. As a result, the correct answer would be...
B. Talking to plants may or may not help plants grow faster because the amount of water given was likely different for each group.