Mastering Java 2026 – 400 Free Practice Questions to Pass the 'Thinking in Java' Exam

A Set does not allow duplicate elements since it adheres to the "unique keys" concept.

C: Queue does not allow duplicate elements since it follows a FIFO (First-In-First-Out) structure.

D: Map can have duplicate values, but not duplicate keys.

B: List is the correct answer because it allows for duplicate elements. This is because list data structures do not have any restrictions on the number of times an element can appear. Therefore, you can have duplicate elements in a list.