The Table Below Describes the Relationship Between the Number of Workers

The table below 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. $$\begin{array} { | c | c | c | } \hline \begin{array} { c } \text { Calls Per } \\\text { Hour }\end{array} & \begin{array} { c } \text { Number of } \\\text { Telephones } \\\text { Per Hour }\end{array} & \begin{array} { c } \text { Number of } \\\text { Workers } \\\text { Per Hour }\end{array} \\\hline 1 & 1 & 2 \\\hline 2 & 1 & 4 \\\hline 6 & 1 & 6 \\\hline 16 & 1 & 8 \\\hline 22 & 1 & 10 \\\hline 24 & 1 & 12 \\\hline\end{array}$$ Given the information in the table above, what is the call center's marginal cost when it goes from making 6 to 16 calls an hour?

A) 50 cents
B) $2
C) $10
D) $20