What type of RAM is commonly used in laptops?

SO-DIMM (Small Outline Dual Inline Memory Module) is the correct answer because it is specifically designed for use in laptops and compact devices where space is limited. SO-DIMMs are smaller in size compared to standard DIMMs, allowing them to fit into the narrow confines of a laptop's motherboard.

SO-DIMM modules fulfill the same purpose as DIMMs, providing temporary data storage for the processor, but their compact design makes them ideal for portable devices. While DIMMs are common in desktop computers due to the larger physical space available, the size and form factor of SO-DIMMs are necessary for the slim design of laptops.

Other types of RAM mentioned serve different roles or are not optimized for laptops specifically. SDRAM and DRAM refer to types of memory technologies, but they do not indicate the form factor, which is a critical consideration for laptop compatibility.