Digital rights management (DRM) is an access control technology used by hardware manufacturers, publishers, copyright holders and individuals to impose limitations on the usage of digital content and devices. It describes the technology that prevents the uses of digital content that were not desired or foreseen by the content provider. DRM does not refer to other forms of copy protection which can be circumvented without modifying the file or device, such as serial numbers or keyfiles. It can also refer to restrictions associated with specific instances of digital works or devices. Answer: C is incorrect. Code signing is the process of digitally signing executables and scripts in order to confirm the software author, and guarantee that the code has not been altered or corrupted since it is signed by use of a cryptographic hash. Answer: A is incorrect. A hypervisor is a virtualization technique that allows multiple operating systems (guests) to run concurrently on a host computer. It is also called the virtual machine monitor (VMM). The hypervisor provides a virtual operating platform to the guest operating systems and checks their execution process. It provides isolation to the host's resources. The hypervisor is installed on server hardware. Answer: B is incorrect. Grid computing refers to the combination of computer resources from multiple administrative domains to achieve a common goal.