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.

Calls Per Hour Number of Telephones Number of Workers Per Hour

$112$

$214$

$616$

$1618$

$22110$

$24112$

If the price of a telephone increases from $$5$ to $$10$ an hour and nothing else changes, then

Select one:

a$.$ average total cost would increase by $$5$ at every level of output.

b$.$ marginal cost would not change.

c$.$ marginal cost would increase by $$5$ at every level of output.

d$.$ total cost would not change.