In operating system terminology, a program that is currently loaded in memory and actively being executed by the CPU is called what?

Introduction / Context:
Operating systems manage many programs at once, scheduling them to run on the CPU and coordinating their use of memory and devices. To describe a program that is actually running, operating systems use a specific term. This question checks your knowledge of that term, which is central to topics like multitasking, process scheduling, and resource management.

Given Data / Assumptions:

• The situation involves a program that is in execution, not just stored on disk.
• The options include Procedure, Function, Process, Instruction, and Thread.
• We assume the standard terminology used in operating system textbooks.
• The focus is on the high level entity that the OS manages.

Concept / Approach:
In operating systems, a process is defined as a program in execution. It includes the program code, current activity, register contents, program counter, stack, and associated resources such as open files. A procedure or function is a block of code within a program, not the entire running entity. An instruction is a single machine level operation, which is much smaller than a program. A thread is a unit of execution within a process, sharing its resources. Therefore, the correct term for a running program is process.

Step-by-Step Solution:
Step 1: Recognise that the question explicitly refers to a program in execution, meaning it is currently running.Step 2: Recall the classical definition from operating system theory: a process is a program in execution.Step 3: Understand that a procedure or function is just a small part of a program, used for modularity and reuse.Step 4: Note that an instruction is one low level machine step, and many instructions together form a program.Step 5: Remember that a thread is a lightweight unit of execution within a process, but the question asks about the program as a whole.Step 6: Conclude that Process is the correct answer.

Verification / Alternative check:
To verify, consider how operating systems are described in textbooks. They discuss process states such as new, ready, running, waiting, and terminated. Each process corresponds to a program that has been loaded and is being executed. Threads are introduced later as subunits of a process that share memory space. Procedures, functions, and instructions are discussed in programming and computer architecture contexts, but the key OS object that represents a running program is always called a process. This consistent usage confirms that process is the correct term.

Why Other Options Are Wrong:
Procedure and Function are programming constructs representing reusable blocks of code inside a program and do not describe the entire running instance managed by the OS. Instruction refers to a single machine code operation, which is far too small in scope to represent a complete program in execution. Thread is a unit of execution employed in multithreaded programs, but a thread exists inside a process and is not synonymous with the entire program. Consequently, none of these alternatives match the standard definition.

Common Pitfalls:
Students may confuse threads with processes because both involve execution and scheduling. Another pitfall is to treat any programming concept, such as a function, as equivalent to a running program. To avoid this, remember the hierarchy: programs on disk become processes when they run, and those processes may contain one or more threads. Instructions are the tiny steps that the CPU performs as it executes the code of a thread within a process.

Final Answer:
In operating system terminology, a program in execution is called a Process.