The OS of a computer may periodically collect all the free memory space to form contiguous block of free space. This is calledSelect one:a.Concatenationb.Garbage collectionc.Collisiond.Dynamic Memory Allocation

The process described in the question is known as "Garbage collection." Let's break down why this is the correct answer:

1. Concatenation: This term generally refers to linking things together in a series or chain. In the context of memory management, it doesn't specifically refer to the process of collecting free memory space into a contiguous block.

2. Garbage collection: This is a form of automatic memory management. The operating system or a runtime environment periodically identifies and reclaims memory that is no longer in use, consolidating free memory into a contiguous block. This helps in optimizing memory usage and preventing fragmentation.

3. Collision: This term is often used in the context of hashing and networking, where it refers to two or more entities attempting to occupy the same space or resource simultaneously. It is not related to memory management in the context described.

4. Dynamic Memory Allocation: This refers to the process of allocating memory storage during the runtime of a program. While related to memory management, it does not specifically describe the process of collecting and consolidating free memory space.

Therefore, the correct answer is:

b. Garbage collection