Install the card already

You are installing a PCI card into a desktop computer, and you notice that there are small spacers inside of the PCI slot. What function do these spacers provide?

A) They keep the PCI adapters at equal distances from each other

B) They ensure proper voltage to the adapter card

C) They accommodate proper cooling of the motherboard

D) They limit the throughput from the PCI bus

E) They are used to keep the small spacer workforce in business