Introduction:
AM (Amplitude Modulation) is a modulation technique used in communication systems to transmit information through changes in the amplitude of a carrier signal. AM detection refers to the process of recovering the original modulating signal from the received AM signal. It involves extracting the modulating signal from the carrier signal.

Explanation:
AM detection serves the purpose of recovering the original modulating signal from the received AM signal. Let's understand the options given in the question:

a) Detecting whether it is modulated:
This option is incorrect because AM detection assumes that the received signal is already modulated. It does not involve detecting whether the signal is modulated or not.

b) Finding the type of modulation:
This option is also incorrect because AM detection assumes that the type of modulation is already known to be Amplitude Modulation. It does not involve determining the type of modulation used.

c) Recovering the modulating signal from the received signal:
This option is correct. AM detection involves extracting the original modulating signal from the received AM signal. The process typically includes removing the carrier signal and any unwanted noise or interference to obtain the original modulating signal.

d) None of these:
This option is incorrect as explained above. AM detection is specifically concerned with recovering the modulating signal from the received AM signal.

Conclusion:
AM detection refers to the process of recovering the original modulating signal from the received AM signal. It does not involve detecting whether the signal is modulated, determining the type of modulation, or any other unrelated tasks. The correct option in this case is option 'C'.