Table 301 Assume That the Product Price Is $4 Per Unit and |

Table 30.1 $$\begin{array} { | c | r | c | c | c | } \hline \begin{array} { c } \text { Number of } \\\text { workers (per } \\\text { hour) }\end{array} & \begin{array} { c } \text { Total output } \\\text { (per hour) }\end{array} & \begin{array} { c } \text { Marginal } \\\text { physical } \\\text { product } \\\text { (output per } \\\text { worker) }\end{array} & \begin{array} { c } \text { Total revenue } \\\text { (dollars per } \\\text { hour) }\end{array} & \begin{array} { c } \text { Marginal revenue } \\\text { product (dollars } \\\text { per hour worker) }\end{array} \\\hline 1 & 4 & \ldots & & \ldots \\\hline 2 & 19 & & \\\hline 3 & 15 & & \\\hline 4 & 19 & & \\\hline 5 & 22 & & \\\hline\end{array}$$ Assume that the product price is $4 per unit and that the hourly wage for workers is $12.Neither price nor wage changes with output.In Table 30.1,the contribution to total revenue of the fourth worker hired is

A) $76 per hour.
B) $16 per hour.
C) $4 per hour.
D) $12 per hour.