If the B - H curves of two samples of X and Y of iron are as shown below, then which one of the following statement is correct?

For a constant hydraulic stress on an object, the fractional change in the object's volume $$\left( {{{\Delta V} \over V}} \right)$$ and its bulk modulus B are related as

A long cylindrical iron core of cross-sectional area 5 cm² is inserted into a long solenoid having 4000 turns/meter and carrying a current 5 A. The magnetic field inside the core is $$\pi$$ T. Find the pole strength developed.