4 GB is the maximum addressable memory in a 32-bit system. Many such systems with 4 GB of RAM installed will only show 3.5 GB (or less) RAM. This discrepancy is due to which of the following? 1. The difference between calculations used by RAM manufacturers and Microsoft. 2. Some addressable space is required for the BIOS/UEFI and I/O devices.3. Microsoft rounded up in their statement of maximum addressable memory. 4. The operating system is consuming part of memory. 5. Overhead needed for the swap file