A Tightly Wound Solenoid Is 15 Cm Long,has 350 Turns,and $\times$

A tightly wound solenoid is 15 cm long,has 350 turns,and carries a current of 3.0 A.If you ignore end effects,you will find that the value of at the center of the solenoid when there is an iron core of magnetization M = 1.4 $\times$ 10⁶ A/m is approximately

A) 11 mT
B) 8.8 mT
C) 1.8 mT
D) 7.0 mT
E) 6.2 mT