Diode Half-Wave Rectification Steps:

• AC supply produces a symmetric sine wave on the oscilloscope.
• Diode in series allows current only during positive half-cycles, blocking negative ones.
• Resulting voltage across the load is the positive half of the sine wave.
• Trace shows half-wave rectified signal with zero during negative periods.

Why A is correct:

• A depicts the half-wave rectified waveform, consistent with diode forward bias passing positive cycles per diode characteristic.

Why the others are wrong:

• B shows full-wave rectification, requiring two diodes or bridge configuration.
• C remains unchanged full sine wave, ignoring diode's blocking effect.
• D inverts the waveform, unrelated to series diode action.

Final answer: A