Which measurement would be taken in millivolts?

The correct answer is voltage, as voltage is measured in volts, and when dealing with very small voltage levels, it is often expressed in millivolts (mV), where one millivolt is one-thousandth of a volt. This scale is particularly useful in various electrical and electronic applications, where minute voltage changes are significant, such as in signal processing or biomedical measurements.

In contrast, current is measured in amperes, resistance in ohms, and power in watts. Each of these measurements has its own unit of measure that reflects the specific electrical property being quantified. Thus, understanding that voltage can be represented in millivolts highlights its typical use in scenarios where precision is needed at low voltage levels.