In a plane electromagnetic wave travelling in free space, the electric field component oscillates sinusoidally at a frequency of $2.0\times10^{10}\ Hz$ and amplitude $48\ Vm^{-1}$. Then the amplitude of oscillating magnetic field is: (Speed of light in free space $=3\times10^8\ ms^{-1}$)
A $1.6\times10^{-6}\ T$
B $1.6\times10^{-9}\ T$
C $1.6\times10^{-8}\ T$
D $1.6\times10^{-7}\ T$