Hardware vs. Software basics.

Application binary interface relates to low level matching of program and system. For exams do not treat it as a normal user screen.

A runtime environment supports a program during execution. For exams understand it as software environment not hardware.

If dependency is missing a program may have trouble running. For exams use library and runtime as examples.

Journaling can help repair file system after sudden shutdown. For exams connect it with relation between storage and software structure.

After mounting the operating system can access files. For exams do not understand mount only as physical fixing.

Safe removal lets the system finish pending file operations. For exams remember the role of unmount in removing a pen drive.

RAID can use multiple disks for performance or data safety. For exams treat it as a storage concept.

Both may aim at storage management but the method differs. For exams identify the form even when the function is similar.

Graphics processing unit performs visual work and driver runs it with the system. For exams separate device and control software.

Hardware acceleration can help in tasks like video or graphics. For exams connect it with performance improvement.

Network card is hardware for sending data while network stack handles rules. For exams separate hardware and protocol layers.

IP address can change while MAC address is considered more directly tied to network interface. For exams identify both addresses separately.

Both can provide security but their form differs. For exams distinguish hardware and software even when function is similar.

Trusted Platform Module can be hardware related to security keys and trust. For exams identify it as an example of security hardware.

Sensor captures sample and template is data stored for matching. For exams separate device and data.

Direct answer: Option A is correct. An encryption key is digital information used by an encryption method to protect data. Encryption changes readable data into an unreadable form, and the key helps an authorised person or system encrypt or decrypt it. The word “key” is being used as a computing concept, not as a button that a finger presses. Option A works because it correctly describes a secret or controlled digital value used in data security. Option B is wrong because a plastic keyboard button is a physical hardware object, while an encryption key is not always physical and is usually represented as bits or characters. Option C is wrong because a printer roller moves paper and has no necessary connection with encryption. Option D is wrong because a monitor cable carries display signals and is also hardware, not security information. Memory cue: encryption key means “security code,” not “keyboard key.”

A sandbox can keep software within controlled limits. For exams connect it with security and isolation.

A virtual machine is created by software but resources come from real hardware. For exams keep virtual and real separate.

A container is a software isolation method for running applications. For exams do not treat it as a physical object by name.

A hypervisor can allocate real hardware resources to virtual machines. For exams understand it as advanced system software.

Names can confuse in hard questions. For exams separate device program data service and setting.

Many levels work together in a computer. For exams understanding layers from hardware to application is very useful.

Microcode is related to very internal control of the processor. For exams understand it as different from normal application software.

Hardware virtualization support can help a hypervisor allocate real resources better. For exams remember the relation between virtual machines and processor features.

Both can be related to deeper system levels than normal app updates. For exams connect such updates with care and control level.