Answer:
Option D
1.1 seconds
Step-by-step explanation:
The whistling sound has a high frequency and a high pitch. This is usually represented by a spike in the frequency-time graph.
The spectrogram is able to show this point on the graph it plots. This will be a point that has the waveforms clustered together as well as increased. These are points of high frequency, as well as pitch.
From the spectrogram, such a point occurs at point D. at 1.1 seconds.