38. Fossil evidence indicates that horses have gradually increased in size over geologic time.
(A) random selection
(B) directional selection
(C) stabilizing selection
(D) disruptive selection
(E) sexual selection
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統計: A(0), B(71), C(32), D(0), E(1) #2189350
統計: A(0), B(71), C(32), D(0), E(1) #2189350