Chapter 23 - Magnetic Flux and Faraday's Law of Induction - Problems and Conceptual Exercises - Page 835: 99

$(C)\ 2.1\times 10^{-4}V$

We know that $\epsilon=(N)|\frac{(B_2-B_1)\pi r^2}{\Delta t}|$ We plug in the known values to obtain: $\epsilon=(4)(\frac{(2.6\times 10^{-5}-1.2\times 10^{-5}\pi)(0.67)^2}{0.38})$ $\epsilon=2.1\times 10^{-4}V$