Final answer:
MEG stands for magnetoencephalogram, a diagnostic tool in medicine that measures the magnetic field of the brain to assess electrical activity, typically using a SQUID sensor. The correct answer is option A).
Step-by-step explanation:
MEG stands for magnetoencephalogram, which is a measurement of the brain's magnetic field. This technology is used to identify abnormal electrical discharges in the brain that produce weak magnetic signals, providing information about brain activity, rather than just its structure. In the medical field, MEG has been utilized for studies in conditions like Alzheimer's disease and epilepsy. Key advancements in instrumentation, such as the superconducting quantum interference device (SQUID), have significantly improved the ability to measure very small magnetic fields. The SQUID operates at liquid helium temperatures and is capable of detecting magnetic fields thousands of times smaller than that of the Earth's.