The Accompanying Table Describes the Relationship Between the Number of Workers

Multiple Choice

The accompanying table describes the relationship between the number of workers hired by a call center each hour and the number of calls the call center can make each hour. The call center has only 1 telephone. The telephone costs the firm $5/hour (regardless of how many calls are made) , and each worker is paid $10 per hour.  
If the price of a telephone increases to from $5 to $10 an hour and nothing else changes, then:

A) total cost would not change.
B) marginal cost would increase by $5 at every level of output.
C) marginal cost would not change.
D) average total cost would increase by $5 at every level of output.