Final answer:
Early repolarization corresponds to Phase 1 of the cardiac action potential, characterized by initial repolarization due to transient outward potassium flow and closed sodium channels, leading up to the plateau phase.
Step-by-step explanation:
The phase of early repolarization is Phase 1. During the cardiac action potential, following the rapid depolarization that occurs in Phase 0 (attributable to the influx of Na+ ions), Phase 1 is characterized by the beginning of repolarization. This is partly because of the closure of sodium channels and the transient outward flow of potassium ions (K+). Phase 1 leads into the plateau phase, which is Phase 2, where the balance between the inflow of calcium ions and the outflow of potassium ions maintains a prolonged depolarized state. Eventually, Phase 3 or the final repolarization occurs due to the opening of potassium channels and the efflux of K+, bringing the membrane potential back towards the resting level. The relative refractory period, which is part of Phase 3, is when the voltage would likely be around -45 mV to -80 mV as the cell begins to recover and may potentially respond to a new stimulus.