Why would you use break-even point

The stock of grommet corporation, a u. s. company, is publicly traded, with no single shareholder owning more than 5 percent of its outstanding stock. grommet owns 95 percent of the outstanding stock of staple inc., also a u. s. company. staple owns 100 percent of the outstanding stock of clip corporation, a canadian company. grommet and clip each own 50 percent of the outstanding stock of fastener inc., a u. s. company. grommet and staple each own 50 percent of the outstanding stock of binder corporation, a u. s. company. which of these corporations form an affiliated group eligible to file a consolidated tax return?