15. If the peak electric field in an electromagnetic wave is 1200 V/m , what is the peak magnetic field for the same wave?
(A)2.2×10−6T 
(B)3.4×10^{−6T 
(C)4.0 ×10−6T
(D)8.7×10−6T 
(E)9.6×10−6T}