$\text { Happy Tots Child Care }$ Price of a Unit of Output

$\text { Happy Tots Child Care }$
$\text { Units of Labor per }~~\text { Output per Week }~~\text { Marginal Product }\\Week~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~per ~Week\\\begin{array}{|c|c|c|}\hline ~~~~~~~~~~~~~~~1~~~~~~~~~~~~~~~~~ & ~~~~~~~~4 ~~~~~~~~~& ~~~~~~~4~~~~~~~~ \\\hline 2 & 9 & 5 \\\hline 3 & 13 & 4 \\\hline 4 & 16 & 3 \\\hline 5 & 18 & 2 \\\hline\end{array}$
Price of a unit of output: $\$ 150$ per week.
Cost to Happy Tots of hiring one more unit of labor: $\$ 400$ per week.
Table 16.1 Refer to Table 16.1.Suppose the cost of child care workers (units of labor) is the only cost the firm faces.How many units of labor would the firm need to hire to maximize profit?

A) 2.
B) 3.
C) 4.
D) 5.