Concept:Every crop has a unique botanical name.Onion is scientifically known as Allium cepa.Explanation:Zea mays is the botanical name for maize.Oryza sativa is the botanical name for rice.Carica papaya is the botanical name for pawpaw.Allium cepa is the botanical name for onion.Thus, the correct match for onion is Allium cepa.Answer:D. Allium cepa