The revenue for the week is $2000, and labor cost consists of two workers earning $8 per hour who work 40 hours each, what is labor cost as a percentage of revenue?

 revenue  = $2000
labor cost per worker working 40 hrs =  8 . 40  =    320
   for  2 workers  =      640
 as a % of revenue      =      ( 640 . 100)/2000      =      32%

The second and fourth answer are correct