Identify the circuit behavior

For a series/combination RC circuit driven by a square wave AC source, the observed output depends on where the output is taken.

In the standard JEE-type question of this form, the RC network acts like a differentiating circuit when the output is monitored across the resistor for a rapidly changing square-wave input.

Effect of square-wave input on an RC differentiator

A square wave has:

• constant positive level for some time,
• then an abrupt jump to negative level,
• then constant negative level,
• then abrupt jump back to positive level.

The derivative of a constant level is zero, while the derivative of a sudden jump is a sharp pulse.

Therefore, the output consists of:

• a positive sharp pulse when the input rises,
• a negative sharp pulse when the input falls,
• nearly zero in between.

Shape across capacitor vs resistor

• Across the capacitor, the output would be a rounded charging/discharging waveform.
• Across the resistor, the output would be narrow alternating spikes.

Since the question asks for the CRO pattern close to the expected RC response to square wave, the correct figure is the one showing alternating sharp pulses at the transitions.

Matching with options

Among the given choices, this corresponds to Option D.

Final answer

$\boxed{D}$