In the context of operating systems, which of the following statements is/are correct with respect to paging?

Let us evaluate each statement:

• (A) is correct: Paging divides physical memory into fixed-size blocks called frames and logical memory into pages of the same size. Since any available frame can be assigned to a process, paging eliminates external fragmentation.

• (B) is incorrect: Internal fragmentation occurs in the last page allocated to a process if the process does not completely fill it. The average internal fragmentation is approximately $\frac{1}{2} \times \text{page size}$, meaning page size directly impacts internal fragmentation.

• (C) is correct: Paging requires page tables to translate logical addresses to physical addresses. These page tables (and multi-level page tables) reside in main memory and consume storage, introducing memory overhead.

• (D) is incorrect: Multi-level paging is designed to break up large, contiguous page tables into smaller pages to avoid allocating massive contiguous physical memory for page tables (handling sparse address spaces efficiently). It is not required for supporting multiple page sizes.

Hence, statements A and C are correct.