The ampere, symbolized as 'A', is the fundamental SI (International System of Units) unit for measuring electric current. Electric current is defined as the rate of flow of electric charge through a conductor. Specifically, one ampere represents the flow of one coulomb of electric charge past a point in a circuit in one second. The question asks for the measure of electrical current flowing, which is precisely what the ampere quantifies.

A. Ohm: The ohm (Ω) is the unit of electrical resistance, which measures the opposition to the flow of current, not the flow itself.

C. Volts: The volt (V) is the unit of electric potential difference or voltage, which is the "pressure" that drives the electric current through a circuit.

D. Watts: The watt (W) is the unit of power, representing the rate at which electrical energy is transferred or consumed per unit of time.

1. Bureau International des Poids et Mesures (BIPM). (2019). The International System of Units (SI) (9th ed.). Section 2.3.1, "The SI base units," p. 132. The official SI brochure defines the ampere: "The ampere, symbol A, is the SI unit of electric current."

2. National Institute of Standards and Technology (NIST). (2019). NIST Special Publication 330: The International System of Units (SI). Section 2.2, "SI base units," Table 1, p. 6. This publication lists the ampere as the base unit for the quantity of "electric current."

3. MIT OpenCourseWare. (2007). Physics II: Electricity and Magnetism, Course 8.02. Lecture Notes, Chapter 4: Electric Current. Section 4.2, p. 4-2. The notes state, "The SI unit of current is the ampere (A), with 1 A = 1 coulomb/sec = 1 C/s." This directly links the ampere to the flow of charge over time.