Answer: Option B
:
B
Thehuman earcan respond to minute pressure variations in the air if they are in the audible frequencyrange, roughly 20 Hz - 20 kHz. It is capable of detecting pressure variations of less than one billionth of atmospheric pressure.
The hertz is defined as onecycle per second. 20Hz means 20 cycles per second. So the audible frequency range for human ear is 20 cycles per second to 20,000 cycles per second. Thus, even if all the options given fall in this range, a human ear is most sensitive to frequencies between 2000Hz to 5000Hz. Hence, option B is correct i.e. 1000cycles/sec