In this task you will be given an answer to a question. You need to generate a question. The answer given should be a correct answer for the generated question.

Ash Wednesday derives its name from the placing of repentance ashes on the foreheads of participants to either the words 'Repent, and believe in the Gospel' or the dictum 'Remember that you are dust, and to dust you shall return.' The ashes may be prepared by burning palm leaves from the previous year's Palm Sunday celebrations.
where did they get the ashes for ash wednesday