Which of the following is the Windows OS that only recognizes 4GB of RAM?

The Home version of Windows, whether 32-bit or 64-bit, does not inherently restrict RAM to 4GB; the limitation is due to the bit architecture, not the edition.

The 32-bit version of the Windows OS can typically only address up to 4GB of RAM due to its memory addressing capabilities. This is a fundamental architectural limitation of 32-bit computing, where memory addresses are represented by 32 bits, allowing for a maximum of 2^32 bytes (4 gigabytes) of addressable space.

The 64-bit OS is designed to recognize and utilize significantly more than 4GB of RAM, far exceeding the 32-bit limitation.

The trial version of Windows, like any other version, will recognize RAM based on its 32-bit or 64-bit architecture, not its trial status.