What is TRUE about a motherboard that supports up-plugging for PCIe adapter cards?

You can put an x8 card into an x16 slot on a motherboard that supports up-plugging for PCIe adapter cards, and it will run at x8 speed. Up-plugging allows you to use a smaller PCIe card in a larger PCIe slot. For example, you could put an x8 card into an x16 slot. However, the card will only run at x8 speed.