Explanation: A sine wave is a fundamental alternating current (AC) waveform that graphically represents a smooth, repetitive oscillation. This waveform is directly analogous to a point moving around a circle. One complete revolution around a circle is defined as 360 degrees. Similarly, one full cycle of a sine wave represents this complete angular rotation. It begins at zero, rises to a positive peak (at 90 degrees), returns to zero (at 180 degrees), drops to a negative peak (at 270 degrees), and finally returns to zero to complete the cycle (at 360 degrees or 0 degrees of the next cycle). Therefore, one complete sine wave cycle spans 360 degrees of phase. The other options represent specific points within a cycle: 90 degrees is the positive peak, 180 degrees is the zero crossing after the positive half-cycle, and 270 degrees is the negative peak.