Which of these magnets is most likely a permanent magnet?

The obvious answer would be Magnet A.

Explanation:

Because it shows in the middle box it say's It is not really magnetized but retain's it's magnetic properties for a long time. it cannot be the others cause Magnet B. doesn't have any information about it being permanent and Magnet C. say's that it is just not magnetized.

luster is not a good characteristic to use by itself because luster is the property of minerals that indicates how much the surface of a mineral reflects light. the luster of a mineral is affected by the brilliance of the light used to observe the mineral surface.