Use the Following to Answer Questions $\text {Table: Value of the Marginal}$

Use the following to answer questions : $\text {Table: Value of the Marginal}$
$\text {Product of Labour at Demand}$

$\begin{array} { cc}\hline \text {Quantity of Labour}&\text {Total Product}\\ \hline 0 & 0 \\ 1 & 20 \\ 2 & 50 \\ 3 & 90 \\ 4 & 120 \\ 5 & 140 \\ 6 & 150 \\ 7 & 150 \\ 8 & 140 \\\hline\end{array}$
-(Table: Value of the Marginal Product of Labour and Demand) Use Table: Value of the Marginal Product of Labour and Demand.In the table,the total product of labour is shown for the hourly production of power cords.Assume that the market for power cords is perfectly competitive.If the price of a power cord is $4 and the market wage rate is $80 per hour,the profit-maximizing quantity of labour is _____ worker(s) .

A) 1
B) 3
C) 5
D) 7