Given the task definition and input, reply with output. In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

Giving the same products as the Peterson reaction, unlike the Knoevenagel and aldol reactions, it is stereoselective and regiospecific. Beta-carotene is synthesized from vitamin A using this reaction in which an aldehyde or ketone reacts with a phosphonium ylide to form an alkene. For ten points, name this eponymous reaction which won its German discoverer a share of a Nobel Prize.
Science