Final answer:
Steganography is the practice of hiding messages within other mediums, such as by altering the least significant bit of an image file, making it undetectable to unintended recipients. It is a technique for secure communication that differs from cryptography, which encrypts messages but does not hide their existence. Hence, the art of hiding the message itself is steganography.
Step-by-step explanation:
Steganography is the art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient, suspects the existence of the message. This field is part of security through obscurity, an approach which aims to secure communication by making the message unreadable to anyone except for the intended parties not by encryption of the message's content, but by hiding the existence of the message. Unlike cryptography, which changes the appearance of the message through encryption, steganography hides the message within another file or medium so it goes undetected.
For example, by altering the least significant bit of an image file, one can embed secret data without making perceptible changes to the image itself. This is akin to the evolution of written communication, like the logographic systems and cuneiform script, which were symbols agreed upon and codified by society to communicate meaning. In the case of steganography, the 'agreement' is exclusive to the sender and recipient, who have knowledge of the hidden message's existence and the means to retrieve it.
Thus, the correct answer to the question is C) Steganography.