TASK DEFINITION: In this task, you're given an open-domain question. Your task is to provide an answer to the given question. There is only one unique answer for each question. Your answer should be short, and refer to an entity, date, number, etc. Do not put your answer in the context of a sentence.
PROBLEM: Where is the descending aorta located in the mediastinum?

SOLUTION: posterior mediastinal cavity

PROBLEM: When is prison break season 5 coming back?

SOLUTION: April 4, 2017

PROBLEM: What is the 1st element in the periodic table?

SOLUTION:
Hydrogen