A. Within the toolbox, click Choose Items and then browse to and select the ContosoControls user control.
B. Within the toolbox, click Choose Items and then browse to and select the ContosoMailer user control.
C. Right-click Web Project, click Add Reference, and then browse to and select the ContosoControls.dll file.
D. Within the toolbox, click Choose Items and then browse to and select the ContosoControls.dll file.