23. In addition to seeds, which of the following characteristics is unique to seed-producing plants?
(A) Pollen
(B) lignin present in cell walls
(C) megaphylls
(D) sporopollenin
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統計: A(1), B(2), C(0), D(2), E(0) #3411507
統計: A(1), B(2), C(0), D(2), E(0) #3411507