Valentine, holiday, and birthday inherit from the class card. in order for the following code to be correct, what type must the reference variable card be? card = new valentine( "a", 14 ) ; card. greeting(); card = new holiday( "b" ) ; card. greeting(); card = new birthday( "c", 12 ) ; card. greeting();

The variable card must be of type Card

Explanation:The reference has to be of the same type of the class. In this case, there are many diferent classes and the common one is Card, as all inherit from it.

proper noun

explanation:

a proper noun is the name of a particular place, person, or thing. england and america are a proper noun because it is a particular place.