Answer:
The correct answer is - C. 2500 - 5000 Hz
Step-by-step explanation:
According to the graph, there is the threshold of audibility curve that exhibits that at 2500 Hz and 5000 Hz, the lowest thresholds of audibility are present. So the sound that is faintest can be heard at 2500 Hz and 5000 Hz.
This is the reason that te humans are sensitive to the crying of the babies as they must cry at 2500 Hz and 5000 Hz frequency and we get their attention easily.