Which of the following combinations are valid?

A SAS drive uses a different connector design and signal protocol than a SATA backplane, making it physically and electrically incompatible.

SAS controllers are designed to be backward compatible with SATA drives, meaning a SATA drive can be physically connected to a SAS controller port and operate, although it will operate at SATA speeds. This compatibility allows for greater flexibility in storage configurations.

A SAS drive cannot connect to a SATA controller because SAS uses a different signal protocol and physical connector keying that is not compatible with a SATA controller.

A SATA drive uses a completely different interface and protocol (SATA) than Fibre Channel (FC), which is used by FC expanders, making them incompatible.