An iron rod of volume \[{{10}^{-4}}{{m}^{3}}\] and relative permeability 1000 is placed inside a long solenoid wound with 5 turns/cm. If a current of 0.5 A is passed through the solenoid, then the magnetic moment of the rod is

• A. \[10\,\,A{{m}^{2}}\]   
• B. \[15\,\,A{{m}^{2}}\]
• C.   Rate of change of momentum 
• D. \[25\,\,A{{m}^{2}}\]