Which type of brain imaging would be best to observe specific mental functions by studying electromagnetic or metabolic activity in the brain, like blood flow?

Question

1. structural imaging (MRI, CT scan, X-ray)
2. functional imaging (PET scan, fMRI)

Answer 1

Functional imaging such as fMRI and PET scans are the best methods to observe metabolic activity in the brain. Example being: fMRI measures brain activity with changes connected to blood flow. fMRI also show structures and their functions such as neural activity.