Answer:
A. PCIe expansion card .
B. U.2 port on the motherboard .
C. M.2 slot on the motherboard.
Explanation:
PCIe expansion cards or slots are connection points on a system used to install computer peripheral devices like riser cards and for testing and using NVME solid state drive adapter cards.
The U.2 ports are used to connect solid state drives to computer systems with the required protocols, electrical specification and physical features of two SATA and PCI express ports. The M.2 ports are also used to connect super fast SSD.