What is the category of event which was taken place in 2020-03-24T12:00:00?
taken place in 2020-03-24T12:00:00 refers to event_date = '2020-03-24T12:00:00'
SELECT T2.category FROM event AS T1 INNER JOIN budget AS T2 ON T1.event_id = T2.link_to_event WHERE T1.event_date = '2020-03-24T12:00:00'