The data structure required to evaluate a postfix expression is --

The data structure required to evaluate a postfix expression is a stack.

• A queue operates on the First In First Out (FIFO) principle, which is not suitable for evaluating postfix expressions.
• A stack operates on the Last In First Out (LIFO) principle. It is ideal for evaluating postfix expressions.
• An array can store elements in a linear sequence, it does not inherently provide the LIFO or FIFO behavior needed for evaluating postfix expressions.
  A linked-list can store elements with dynamic memory allocation, but it also does not inherently provide LIFO or FIFO behavior needed for postfix evaluation.