Final answer:
The best diagnostic test to discover abnormalities in brain waves is EEG (electroencephalography), which involves recording brain activity using electrodes on the scalp.
Step-by-step explanation:
The diagnostic test that would be best suited to discover any abnormalities in brain waves is the EEG (electroencephalography).
EEG involves taping electrodes to the scalp to record brain activity, allowing neurologists to identify any irregularities in brain waves, such as seizure activity or abnormal patterns. Other options like MRI scan, X-ray, and blood tests are not specific to brain wave abnormalities.