Which parameter affects receiver sensitivity?

Receiver sensitivity is a measure of how well a receiver can detect very weak signals, and it is determined by a combination of several circuit stages. The input amplifier's noise figure determines the fundamental noise floor added by the receiver itself; a lower noise figure means better sensitivity. Additionally, the demodulator stage bandwidth dictates how much overall noise is let through alongside the signal—wider bandwidths let in more noise, which drowns out weak signals. Finally, the input amplifier gain ensures the weak signal is boosted enough to overcome the inherent noise of subsequent stages. Because all three parameters directly dictate the signal-to-noise ratio, all choices are correct.