Which of the following standards is an expansion card slot used only for graphics?

PCIe (PCI Express) is a general-purpose high-speed serial expansion bus used for graphics cards, network adapters, SSDs, and many other devices - not exclusively graphics.

AGP was introduced by Intel in 1996 as a dedicated, high-bandwidth slot specifically for graphics cards, separate from the shared PCI bus. Because it was a point-to-point channel directly between the GPU and the system chipset, it was not used for any other type of expansion card, making it the only slot standard in the list designed solely for graphics.

PCI (Peripheral Component Interconnect) is a general-purpose parallel bus used for a wide variety of expansion cards including NICs, sound cards, and modems.

miniPCI is a smaller form-factor version of PCI used inside laptops for various expansion purposes such as wireless cards, not exclusively for graphics.