Assuming the swap file /swapdir/swapfile1 has been created, which command can be used to add this file to the available swap space?

A.
swapadd /swapdir/swapfile1

B.
swap -a /swapdir/swapfile1

C.
mount -a /swapdir/swapfile1 /swap

D.
growfs /swap -f /swapdir/swapfile1