Answer:
1: the negative battery terminal
Step-by-step explanation:
When we design and develop an electrical circuit in electrical and electronics engineering, it is important that we define a reference point for all electronic signals from which we can measure voltage. Although, the voltage passing through a reference point in an electrical circuit is typically 0 Volts.
Also, a ground is a common return path in an electrical circuit for the current flowing through the circuit.
When working on a direct current (DC) circuit that is mainly operated using a battery, the negative terminal of the battery would be the ground (reference point) for all the components connected to the electrical circuit.
Hence, in the context of electronics, the term "ground" is often used to refer to the negative battery terminal.