What distinguishes a process from a thread?

• A. A thread is an executing program with its own memory; a process is a smaller unit of a process that can run concurrently.
• B. A process is an executing program with its own memory; a thread is a smaller unit of a process that can run concurrently.
• C. A thread has its own independent memory space separate from the process.
• D. A process runs within a thread and shares memory with other processes.

Answer: (B)

The main idea is that a process is an executing program that has its own separate memory space, while a thread is a lightweight path of execution inside a process that uses that same memory. Because all threads in a process share the process’s memory and resources, they can work on shared data efficiently, which makes concurrency within a single process straightforward but requires coordination to avoid conflicts. In contrast, different processes have isolated memory, so communication between them is more explicit and typically heavier.

The statement that fits this precisely is that a process is an executing program with its own memory, while a thread is a smaller unit of a process that can run concurrently. The other descriptions mix up where memory belongs or how the relationship works—for example, a thread does not have its own independent memory space separate from the process, and a process does not run inside a thread.