Consider the Following Production and Cost Schedule for a Firm

Consider the following production and cost schedule for a firm.The first column shows the number of units of a variable factor of production employed by the firm. $\begin{array}{|c|c|l|}\hline \begin{array}{c}\text { Total Number of } \\\text { Units of theFactor }\end{array} & \begin{array}{c}\text { Total Numb er of } \\\text { Units of Output }\end{array} & \begin{array}{c}\text { Price per Unit } \\\text { of Output }\end{array} \\\hline 10 & 20 & \$ 10 \\\hline 11 & 44 & \$ 10 \\\hline 12 & 64 & \$ 10 \\\hline 13 & 78 & \$ 10 \\\hline 14 & 84 & \$ 10 \\\hline 15 & 86 & \$ 10 \\\hline\end{array}$ TABLE 13- 1
-Refer to Table 13- 1.The total revenue of the output produced by 15 units of the factor is

A) $1440.
B) $780.
C) $860.
D) $150.
E) $640.