Given the task definition and input, reply with output. In this task, you are given a context, a subject, a relation, and many options. Based on the context, from the options select the object entity that has the given relation with the subject. Answer with text (not indexes).

Context: Disk encryption software is computer security software that protects the confidentiality of data stored on computer media (e.g., a hard disk, floppy disk, or USB device) by using disk encryption., Disk encryption is a technology which protects information by converting it into unreadable code that cannot be deciphered easily by unauthorized people. Disk encryption uses disk encryption software or hardware to encrypt every bit of data that goes on a disk or disk volume. Disk encryption prevents unauthorized access to data storage., PGP Virtual Disk is an Disk encryption system that allows one to create a virtual encrypted disk within a file . Older versions for Windows NT were freeware ( for example , bundled with PGP v6.0.2i ; and with some of the CKT builds of PGP ) . These are still available for download , but no longer maintained . Today , PGP Virtual Disk is available as part of the PGP Desktop product family , running on Windows 2000/XP/Vista , and Mac OS X., The bit is a basic unit of information in computing and digital communications. A bit can have only one of two values, and may therefore be physically implemented with a two-state device. These values are most commonly represented as either a . The term "bit" is a portmanteau of binary digit. In information theory, the bit is equivalent to the unit "shannon", named after Claude Shannon., In cryptography, encryption is the process of encoding messages or information in such a way that only authorized parties can access it. Encryption does not of itself prevent interference, but denies the intelligible content to a would-be interceptor. In an encryption scheme, the intended information or message, referred to as plaintext, is encrypted using an encryption algorithm, generating ciphertext that can only be read if decrypted. For technical reasons, an encryption scheme usually uses a pseudo-random encryption key generated by an algorithm. It is in principle possible to decrypt the message without possessing the key, but, for a well-designed encryption scheme, large computational resources and skill are required. An authorized recipient can easily decrypt the message with the key provided by the originator to recipients but not to unauthorized users., Subject: pgpdisk, Relation: instance_of, Options: (A) algorithm (B) code (C) computer security (D) cryptography (E) data (F) digit (G) disk (H) disk encryption software (I) encoding (J) information (K) information theory (L) interference (M) key (N) message (O) principle (P) process (Q) security (R) technology (S) volume

disk encryption software