Answer:
a spring.
Explanation:
An electric circuit can be defined as an interconnection of electrical components which creates a path for the flow of electric charge (electrons) due to a driving voltage.
Generally, an electric circuit consists of electrical components such as resistors, capacitors, battery, transistors, switches, inductors, etc.
This electrical network which is usually a closed loop comprises of a device that provides the energy (voltage) to drive electrons or electric current; the device is referred to as a source such as a generator or battery.
Springs are points from which water naturally seeps from the ground. A spring is the original point or most common type of source from which a river flows or begin its journey.
This ultimately implies that, a spring serves as a source to a river flowing with water while a battery or generator serves as a source to an electric circuit with current flowing through it.
Hence, if we compare an electric circuit to a river flowing with water, a spring is considered to be a most likely source to the river.