What is a List in Java?

A List in Java is defined as an ordered collection that allows duplicate elements. This means that when you store elements in a List, they retain their insertion order, and you can add multiple occurrences of the same element without any restrictions.

For instance, if you were to insert the number 5 into the List three times, it would maintain each of those instances with their respective positions in the sequence. This characteristic is valuable in scenarios where the sequence of entries is significant, and duplicity in values is permissible.

The nature of Lists is foundational for certain operations, like accessing elements by their index, which is consistent with how Lists manage order. In Java, the List interface is implemented by various classes such as ArrayList, LinkedList, and others, each suited for different needs regarding performance and access patterns.

The other choices refer to collections with different properties that do not align with the definition of a List in Java.