Answer:
The answer is letter c, The structure of individual neurons.
Explanation:
Brain-imaging technique- this comprises of different techniques for analyzing the brain's activities as well as structure, function and other problems.
There are many brain-imaging techniques such as Positron Emission Tomography or PET, which traces the part of the brain that is activated during specific tasks as well as the localization of brain activity in response to a specific stimulus. These areas are seen with high radioactivity.
Patterns of blood flow in the brain can be detected by using MRI (Magnetic Resonance Imaging) test. There is an increase in blood flow to areas in the brain with high activity level.
With the explanation given, it shows that letter c is the only choice that the brain-imaging techniques cannot determine.