The Table Below Shows the Total Production for Varying Numbers

The table below shows the total production for varying numbers of hours worked producing yo- yos.The firm sells its product and hires its workers in competitive markets. $$\begin{array} { | c | c | c | c | } \hline \begin{array} { c } \text { Number of } \\\text { Hours Worked }\end{array} & \begin{array} { c } \text { Number of } \\\text { Yo-Yos } \\\text { Produced }\end{array} & \begin{array} { c } \text { Wage Rate } \\\text { per Hour } ( \$ ) \end{array} & \begin{array} { c } \text { Price of Yo- Yos } \\( \$ ) \end{array} \\\hline 10 & 60 & 10 & 5 \\\hline 11 & 70 & 10 & 5 \\\hline 12 & 78 & 10 & 5 \\\hline 13 & 84 & 10 & 5 \\\hline 14 & 88 & 10 & 5 \\\hline 15 & 90 & 10 & 5 \\\hline\end{array}$$ TABLE 13- 4
-Consider labour that is hired for $18 per hour.If the last hour of labour hired produces 8 units of output which sells for $10 per unit,that labour- hour's marginal revenue product is

A) $1.20.
B) $144.
C) $80.
D) $4.44.
E) $64.