A car drives onto a loop detector and increases the downward component of the magnetic field within the loop from $1.2 \times 10^{-5} \mathrm{T}$ to $2.6 \times 10^{-5} \mathrm{T}$ in $0.38 \mathrm{s} .$ What is the induced emf in the detector if it is circular, has a radius of $0.67 \mathrm{m},$ and consists of four loops of wire?
A. $0.66 \times 10^{-4} \mathrm{V}$
B. $1.5 \times 10^{-4} \mathrm{V}$
C. $2.1 \times 10^{-4} \mathrm{V}$
D. $6.2 \times 10^{-4} \mathrm{V}$