In △ ABC, it is known that ∠ cab = 60 °, D and E are points on edges AB and AC respectively, and ∠ AED = 60 °, ed + DB = CE, ∠ CDB = 2 ∠ CDE, then ∠ DCB = () A. 15°B. 20°C. 25°D. 30°

If BF ∥ de intersects AC with F, then BD = EF, then EC = de + BD = AB = BF, de = FC, and ∥ EDC ≌ FCB, ≌ θ + x = φ; ∫ CDB = 2 φ, ≌ BDE = 120

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