Which of the following can be substituted for ${?}^{****}{A}^{****}$ and ${?}^{****}{B}^{****}$ to complete the action plan below for replacing a motherboard?

Open the case.

Disconnect connections from the motherboard headers.

$**A^{****}$

Remove or detach motherboard restraints.

Remove the motherboard.

$**B****$

Install the new motherboard.

Attach the connectors to the motherboard headers.

Install chips, modules, and adapter cards on new motherboard.

Reinstall all other components that were removed.

Close case and boot computer to test.

$B=$ Line up the new motherboard with the matching attachment points in the chassis.

$A=$ Disconnect data and power cables from all internal drives.

$A=$ Remove all components except the motherboard from the system unit.

$B=$ Remove all chips, modules, and adapter cards from the old motherboard and place the motherboard in the trash.

$A=$ Remove components obstructing the removal of the motherboard.