The correct answer to this open question is the following.
Although there are no options attached, we can say the following.
If Amanda has plans to investigate how the brain sends messages to the body and wants to conduct an experiment that measures the reaction time of humans in different situations, she needs to do more research based on previous research not only in the United States but in different parts of the world.
She could consult valuable information in the Organization of Human Brain Mapping (OHBM) that specializes in research in neuroimaging. A good news site regarding the brain is "brain mapping." Many scientists and researchers publish their reports here. Another good place for Amanda to investigate is the UCLA School of Medicine, especially the Department of Neurology because it manages the Laboratory of Neuro Imaging. Here, researchers have studied how the brain sends messages to the body.