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.

When is the last time liverpool won the premier league?
1989-90

Which element begins the fourth group of the periodic table?
Titanium

What are the main organs in the lymphatic system?

thymus and the bone marrow