What kind of memory module is inserted into a motherboard at a 45-degree angle?

The correct answer is SODIMM. SODIMM, which stands for Small Outline Dual Inline Memory Module, is specifically designed for laptops and compact devices where space is at a premium. The distinctive 45-degree angle at which SODIMMs are inserted into the motherboard helps ensure that they fit snugly and securely in the limited space available within laptops compared to the traditional DIMM modules found in desktop systems, which are usually installed perpendicular to the motherboard.

In contrast, DIMMs are typically straight and installed perpendicularly in desktop motherboards, while RDRAM refers to a specific type of memory technology that does not have a specific installation angle like SODIMM. DDR3 is a standard type of memory rather than a physical module specification, so while it could refer to DIMMs or SODIMMs configured for use in certain devices, it does not inherently describe the installation angle characteristic of SODIMM modules.