45. There are two parallel-plate capacitors with same plate area A. As the figure illustrated, C1 is filled with two materials of dielectricconstants κ and 2κ, while C2 is filled with only one material. The capacitance ratio C1 / C2 is___________ .
(A) 0.5
(B) 1.0
(C) 1.5
(D) 2.0
(E) 2.5