Answer:
variable manufacturing cost per unit = $142.70
so correct option is C) $142.70
Step-by-step explanation:
solution
we get here first direct materials cost per unit that is express as
direct materials cost per unit = Change in cost ÷ Change in activity   .......1
put here value 
direct materials cost per unit =  
 
direct materials cost per unit  = $97.10 per unit  
and now we get here direct labor cost per unit that is 
Direct labor cost per unit = Change in cost ÷ Change in activity   ........2
Direct labor cost per unit =  
 
Direct labor cost per unit = $22.70 per unit
and 
now we get variable manufacturing overhead per unit that is 
variable manufacturing overhead per unit = Change in cost ÷ Change in activity  .........3
variable manufacturing overhead per unit =  
 
variable manufacturing overhead per unit = $22.90 per unit  
so that  total variable manufacturing cost per unit will be 
total variable manufacturing cost per unit = 22.90 + $22.70 + $97.10 total variable manufacturing cost per unit = $142.70
so correct option is C) $142.70