Wheat belongs to genus Triticum. Triticum represents to free-threshing wheat. Family Poaceae or Gramineae is a big and nearly universal family of grasses. It contains cereal grasses and the flowers in the family are typically small, enclosed by bracts, and are arranged in inflorescence. Order Poales contains species whose flowers are wind pollinated (mostly). Other than that seeds are usually stored with starch like in wheat and rice. Class Monocotyledonae contain seed plants that develop an embryo with a single cotyledon and parallel-veined leaves. It includes grasses, lilies, palms, and orchids.
Thus, the correct option is 'Genus: Triticum, Family: Poaceae, Order: Poales, Class: Monocotyledonae'.