The term that designates any equipment that may be added to a computer system to enhance or extend its functionality is what?

Introduction / Context:
This question is closely related to the earlier question on peripherals. It asks for the formal term used to describe equipment that can be connected to a computer system in order to add new features. Such equipment might include printers, scanners, external drives, game controllers and many other devices that are not strictly required for the computer to function but significantly expand its capabilities.

Given Data / Assumptions:

• The equipment is added to an existing computer system.
• Its purpose is to enhance or extend functionality.
• Options list digital device, system add on, disk pack, peripheral device and control panel.
• We assume a standard classification of hardware components.

Concept / Approach:
Peripheral device is the standard term for any external or additional device that connects to a computer. This includes both input devices, such as keyboards and scanners, and output devices, such as printers and monitors, as well as storage and communication hardware. Phrases like digital device or system add on are generic and are not the formal term used in textbooks. Disk pack refers to storage media and control panel refers to a part of the user interface or physical controls, not to the full class of add on equipment.

Step-by-Step Solution:
Step 1: Identify that the question is asking for a general term, not a specific example. Step 2: Think of devices like printers, speakers, webcams and external drives that are connected to a computer system after purchase. Step 3: These devices are usually referred to as peripheral devices or simply peripherals. Step 4: Option d, peripheral device, exactly matches this broad category. Step 5: Digital device is too general and could refer to any electronic gadget, including those unrelated to computers. Step 6: System add on sounds like an informal phrase and is not the standard textbook term. Step 7: Disk pack refers to a particular type of storage media, not all kinds of equipment that can be added to a system. Step 8: Control panel is usually the name of a software utility or physical panel of switches, not the devices themselves.

Verification / Alternative check:
Computer hardware diagrams and manuals consistently use the word peripheral to describe devices like printers or external drives. The term peripheral device appears in exam syllabi and question banks as the label for hardware added to the system. In contrast, system add on is seldom used as a formal concept in basic computer science texts. This consistent usage confirms that peripheral device is the correct term the question is seeking.

Why Other Options Are Wrong:
Digital device could refer to cameras, watches or any other modern gadget and does not emphasise connection to a computer system. System add on lacks precision and is not a standard category. Disk pack refers to storage media only and fails to include non storage devices. Control panel typically refers to a user interface or settings module, either hardware or software, and not to the broad set of hardware peripherals.

Common Pitfalls:
Students may be tempted by system add on because it sounds similar to the description in the question. However, exams usually expect formal terminology that appears in textbooks, not informal guesses. To avoid this pitfall, always recall whether a term is used formally in definitions and diagrams instead of selecting a phrase that merely sounds right.

Final Answer:
Equipment added to a computer system to enhance its functionality is called a peripheral device.