The electroencephalography performs which of the following functions?

Electroencephalography (EEG) is a diagnostic tool that primarily measures the brain's electrical signals. It records the electrical activity of the brain using electrodes placed on the scalp, capturing the brain's rhythmic fluctuations that correspond to mental activities and states. This function is crucial for diagnosing various neurological conditions such as seizures, sleep disorders, and other brain-related issues. In contrast, the other functions mentioned, such as assessing spinal cord irregularities, measuring peripheral muscle activity, or evaluating spinal fluid levels, fall under different types of diagnostic tests and procedures, such as MRI for imaging the spinal cord, electromyography (EMG) for muscle activity, and lumbar punctures for spinal fluid analysis, respectively. Thus, the correct choice underscores the specific role of EEG in examining and interpreting the brain's electrical function.