Which of the following is a difference between PCI-X and PCI-e expansion slots?

A.
PCI-X cards are replacing AGP video cards

B.
PCI-X cards operate on a higher bandwidth than PCI-e cards for data transfer

C.
PCI-X cards will fit in older PCI slots, but PCI-e will not

D.
PCI-e cards will fit in older PCI slots, but PCI-X will not