Except the correct answer is d. They all have a MAC address.
They all have at least one MAC address![]()
/sigh kids today, no, no they don't

A hub (AKA a multi-port repeater) is a "dumb" device and has no mac, it simply receives the incoming signal on one port then repeats it on every port. Hubs haven't actually been produced/used in quite a while now, it's just many people (including whoever came up with the question) have difficulty differentiating between hubs and switches.