A car drives onto a loop detector and increases the downward component of the magnetic field within

Question:

A car drives onto a loop detector and increases the downward component of the magnetic field within the loop from 1.2 × 10-5 T to 2.6 × 10-5 T in 0.38 s. What is the induced emf in the detector if it is circular, has a radius of 0.67 m, and consists of four loops of wire?

A. 0.66 × 10-4 V

B. 1.5 * 10-4 V

C. 2.1 × 10-4 V

D. 6.2 × 10-4 V