Correct option is B
At low frequencies, the gain of a BJT amplifier decreases due to the high reactance of the coupling and bypass capacitors.
Coupling capacitors are used to pass the AC signal between amplifier stages while blocking DC, preventing the DC bias of one stage from affecting another. At low frequencies, their impedance increases, reducing the amount of signal passed to the next stage.
Bypass capacitors are connected in parallel with emitter resistors to provide a low-impedance path to ground for AC signals, effectively shorting the emitter resistor at midband and high frequencies to maximize gain. At low frequencies, their impedance increases and the emitter resistance is no longer effectively bypassed, which increases negative feedback and decreases the amplifier's gain.
