Correct : c

The circuit is an RC series high-pass filter with output taken across R. Since R and C are both very large, the time constant τ = RC is extremely large. The input is a very high frequency square wave, meaning the period T is very small compared to τ.
The condition T << τ means the capacitor voltage barely changes during each half cycle — the capacitor does not have enough time to charge or discharge significantly. The output voltage V_out = V_in − V_C. Since V_C remains nearly constant, V_out faithfully tracks V_in and the output is essentially the same square wave as the input with only negligible exponential droop at the top and bottom of each pulse.
This is the classic pass-through behaviour of a high-pass filter at very high frequencies — the capacitor acts almost as a short circuit (cannot change voltage fast enough) so the full input appears across R. The output waveform looks like a square wave that almost perfectly reproduces the input.
Correct answer: C ✓