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: When does crossing over occur in prophase 1?

SOLUTION: pachytene stage

PROBLEM: When was the last time the us constitution changed?

SOLUTION: May 5, 1992

PROBLEM: When did the nba start using a shot clock?

SOLUTION:
1954