Ⅱ.【單選題】51-75 題，每題 2 分，共計 50 分。答錯 1 題倒扣 0.5 分，倒扣至本大題零分為止，未 作答，不給分亦不扣分。
51. Which of the following statement about plant flower is correct?
(A) A flower is the vegetative organ of a plant.
(B) A flower lacking any of sepal, petal, stamen or carpel is an imperfect flower.
(C) Most grasses have imperfect flowers.
(D) Floral parts in all angiosperm are arranged as four whorls.
(E) Floral parts are sequentially initiated at the floral meristem.