Which best differentiates a process from a thread in an operating system?

Which best differentiates a process from a thread in an operating system?

• A. A thread has its own memory; a process shares memory.
• B. A process has its own memory space; a thread is within a process and shares memory.
• C. A process executes in kernel mode only; a thread executes in user mode only.
• D. Processes are always faster than threads.

Answer: (B)

The key idea is how memory is organized for processes versus threads. A process has its own separate memory space, which provides isolation from other processes. A thread, on the other hand, runs within a process and shares that process’s memory and resources with its sibling threads. This memory sharing is what makes threads lighter weight and faster to switch between, but it also requires synchronization to avoid data races. That’s why the correct choice is that a process has its own memory space, while a thread is within a process and shares memory. The other statements don’t fit: memory ownership is reversed in the first option, threads can run in either user or kernel mode depending on the system (and many threads run in user mode), and processes are not inherently faster than threads—threads are typically cheaper to create and switch between.

The key idea is how memory is organized for processes versus threads. A process has its own separate memory space, which provides isolation from other processes. A thread, on the other hand, runs within a process and shares that process’s memory and resources with its sibling threads. This memory sharing is what makes threads lighter weight and faster to switch between, but it also requires synchronization to avoid data races.

That’s why the correct choice is that a process has its own memory space, while a thread is within a process and shares memory. The other statements don’t fit: memory ownership is reversed in the first option, threads can run in either user or kernel mode depending on the system (and many threads run in user mode), and processes are not inherently faster than threads—threads are typically cheaper to create and switch between.