How to get a value from a table that a value is referenced from?
SELECT  a.question,
        a.answer
FROM    Answers a
INNER JOIN Questions q 
    ON q.id = a.question
WHERE a.answer = 1


The JOIN syntax is described in the PostgreSQL documentation "2.6. Joins Between Tables"

(emphasis mine)


  A query that accesses multiple rows of the same or different tables at one time is called a join query.