Answer:
B. If a plant is turned upside down, which way will the roots grow?
Step-by-step explanation:
A scientific experiment needs to investigate something, to be established later. For this reason, it is important that when carrying out an experiment, a "testable question" is established so that an answer with scientific confirmation is sought.
This testable question must be something that we do not know the answer to, as it is up to the experiment to answer and show facts that prove it. For this reason, we can say that among the options given in the question above, option "B" shows a coherent testable question for an experiment.