Answer:
The answer is 'D'- only port replicators have expansion slots.
Explanation:
A port replicator is a kind of attachment which allows multiple devices to be attached to the laptop through a simple USB. The devices can be a monitor, printer, large monitor, keyboard etc.
On the other hand a docking station allows portable computers to be connected to other hardware devices and get converted into a desktop system. Docking station can be plugged hot or cold. Cold docking is carried out when the system is shut down and hot docking occurs when the system is still running and the docking station is connected.