Select the Venn diagram that best illustrates the relationship between the following classes:
$$\text{Panther, Bird, Eagle}$$

Every 'Eagle' belongs entirely to the class of 'Bird', meaning the circle for Eagle must be fully enclosed within the larger circle representing Birds. A 'Panther' is a mammal and shares no characteristics with birds or eagles, so its circle must be drawn completely separate from the other two.
Therefore, the relationship is best depicted by one circle inside another, along with an entirely separate third circle.