Which measurement would be taken in millivolts?

Voltage is the correct measurement that would be taken in millivolts. The voltage level is often expressed in volts (V), but for smaller values, it's common to use millivolts (mV), where 1 millivolt is equal to one-thousandth of a volt. This unit of measurement is frequently used in electronics and electrical engineering to represent low voltage signals, such as those found in sensors, amplifiers, and microcontrollers.

Current is typically expressed in amperes (A), while resistance is measured in ohms (Ω). Power is commonly represented in watts (W). Since each of these measurements has its specific units, understanding that voltage can be measured in millivolts helps highlight the context in which this unit is applicable, particularly when dealing with low-voltage applications in various technologies.