As Shown in the Figure,two Solenoids Are in Line

Multiple Choice

As shown in the figure,two solenoids are in line.The switch S,initially closed,is suddenly opened.Just after opening S,what is the polarity of the induced emf in terminals X and Y?

A) X and Y are at the same potential.
B) X is positive and Y is negative.
C) Y is positive and X is negative.