I answered 'Creatures', which is correct. It does not score as such.
'Creatures' and 'Emblems' are both correct. Commanders, which can be placed in your Command Zone, are creatures, therefore, creatures are a legal card type that can be placed in your Command Zone.
This question is unclear. The "Command Zone" in a game of EDH or Commander is a place reserved for Legendary Creatures that act as your "commander" for the game. So when it asks "which of these card types can be placed in the command zone" the way you have worded it, "creatures" is a correct answer in a game of EDH. Consider revising.
What is the difference between public and private zones?