To answer this question, you need to understand the concept of a Java Map.
Option A) A vector of arrays for a 2D geographic representation - This option is incorrect because a Java Map is not specifically designed for representing 2D geographic data.
Option B) A class for containing unique array elements - This option is incorrect because a Java Map is not specifically designed for containing array elements.
Option C) A class for containing unique vector elements - This option is incorrect because a Java Map is not specifically designed for containing vector elements.
Option D) An interface that ensures that implementing classes cannot contain duplicate keys - This option is correct because a Java Map is an interface that ensures that implementing classes cannot contain duplicate keys. In other words, a Java Map is a data structure that stores key-value pairs and guarantees that each key is unique.
The correct answer is Option D.