A receptacle mounted Ground Fault Circuit Interrupter protects against which of the following?

A Ground Fault Circuit Interrupter (GFCI) is specifically designed to protect against current flow to ground. It serves as a safety device that detects imbalances in the electrical current. When there is a ground fault, which occurs when current escapes the intended path and travels through an unintended route, such as through a person's body to the ground, the GFCI will quickly shut off the circuit. This mechanism helps to prevent electric shock and potential electrocution.

While the other options may involve electrical issues, they do not accurately describe the primary function of a GFCI. Overcurrent flow refers to excessive current that can lead to overheating and damage to equipment but is protected by circuit breakers. Short circuits involve a direct path for current flow, which leads to high current flow but also falls under the protection of circuit breakers and fuses. Voltage fluctuations deal with changes in the electrical supply, impacting devices but do not specifically pertain to ground faults. Thus, current flow to ground is the essential focus and protective feature of a GFCI.