The relative permeability of the core of a solenoid is 400. The windings of the solenoid are insulated from the core and carry a current of 2 A. The number of turns per meter is 1000. if the core is replaced by another material of relative permeability of 200, the magnetic field of new solenoid will be ________ by ________% of its previous value. Choose the correct option to fill the respective blanks.