The small energy losses in transformers due to eddy currents can be reduced by

$A$ sheet is placed on a horizontal surface in front of a strong magnetic pole. $A$ force is needed to:
$A$. hold the sheet there if it is magnetic.
$B$. hold the sheet there if it is non-magnetic.
$C$. move the sheet away from the pole with uniform velocity if it is conducting.
$D$. move the sheet away from the pole with uniform velocity if it is both,non-conducting and non-polar.
Choose the correct statement$(s)$ from the options given below:

The core of a transformer is laminated so that

$A$ magnet is dropped down an infinitely long vertical copper tube.

Consider a metallic pipe with an inner radius of $1 \ cm$. If a cylindrical bar magnet of radius $0.8 \ cm$ is dropped through the pipe,it takes more time to come down than it takes for a similar unmagnetised cylindrical iron bar dropped through the metallic pipe. Explain.

$A$ magnet is dropped down an infinitely long vertical copper tube. Then