What is spyware in the context of computer software?

• A. Software whose purpose is to collect information about a person without his knowledge and can send such information to another entity.
• B. Legitimate software that allows companies to control and maintain their employees' computers from a central location.
• C. Software that is used to disrupt the operation of a computer or to gain access to a personal computer system.
• D. A computer program hidden within another harmless virtual program that copies itself and attaches to other programs or files.