When the secondary winding of a current transformer is open-circuited with the primary winding energized.

• A. the whole of the primary current produces large value of flux in the core (limited only saturation) there by producing a large voltage in the secondary winding.
• B. the large voltage may act as safety hazard for the operators and many even rupture the insulation
• C. the large magnetizing force is taken-Off, it leaves a large value of residual magnetism
• D. All of the above