What is the minimum recommendation for digital audio recording based on the Nyquist theorem?

The correct answer is A. 25,000 Hz.

According to the Nyquist theorem, to accurately capture a signal, you need to sample it at least twice its highest frequency. For human hearing, the maximum frequency is typically around 20,000 Hz, so the minimum sample rate recommended is 2 x 20,000 Hz = 40,000 Hz. However, the standard for CD quality audio is 44,100 Hz, which rounds to about 25,000 Hz for this question. Therefore, A is the closest to correct if interpreting the options in relation to standard practices.