Shared memory is a mechanism that allows multiple processes to access and manipulate the same region of memory. It is a form of inter-process communication (IPC) that enables processes to share data and communicate with each other. The main function of shared memory is to facilitate inter-process communication, making option C the correct answer.

Shared memory is a widely used technique in operating systems and parallel computing environments. It provides a fast and efficient way for processes to exchange information and collaborate on tasks. Here are the key points explaining why shared memory is primarily used for inter-process communication:

Efficient Memory Utilization:
- Shared memory allows multiple processes to access the same physical memory region. This eliminates the need for copying data between processes, which can be time-consuming and resource-intensive.
- By sharing a common memory space, processes can directly read from and write to the shared memory, resulting in faster and more efficient communication.

Synchronization and Coordination:
- Shared memory provides a shared data structure that can be used for synchronization and coordination between processes.
- Processes can use synchronization primitives such as locks, semaphores, or condition variables to control access to the shared memory region, ensuring that only one process modifies the data at a time.

Flexible Communication:
- Shared memory allows processes to communicate using a wide range of data structures and formats. Processes can share simple variables, arrays, or complex data structures such as queues, buffers, or graphs.
- This flexibility enables processes to exchange data of different types and sizes, making shared memory suitable for a wide range of inter-process communication scenarios.

High Performance:
- Shared memory is a high-performance communication mechanism since it relies on direct memory access rather than slower IPC mechanisms like message passing.
- Processes can access shared memory with low overhead, making it ideal for scenarios where high-speed communication is required, such as parallel computing or real-time systems.

In conclusion, the main function of shared memory is to enable inter-process communication, allowing processes to share data and collaborate efficiently. Shared memory provides efficient memory utilization, synchronization, flexible communication, and high performance, making it a widely used mechanism in various computing environments.