(a) Steganography has been used for quite a while, since World War II time. It was heavily used for communication among allies in order to prevent information being captured by enemies

i. Propose ONE (1) most widely used approach to hide a secret message in a PNG image file as a carrier and justify your answer.

ii. Identify ONE (1) weakness of the proposed approach in question (b)(i).

iii. Explain ONE (1) challenge encountered in audio steganography.