A Manufacturing Firm Is the Sole Seller of a Specialized

A manufacturing firm is the sole seller of a specialized machine. The demand schedule for this product is shown in the table below.

$\begin{array} { | c | c | c | c | c | c | c | c | } \hline \text { Price } & \$ 700000 & \$ 600000 & \$ 500000 & \$ 400000 & \$ 300000 & \$ 200000 & \$ 100000 \\\hline \begin{array} { c } \text { Quantity } \\\text { Demanded }\end{array} & 0 & 1 & 2 & 3 & 4 & 5 & 6 \\\hline\end{array}$
-For this firm,the marginal revenue of the fourth machine is:

A) $600 000
B) $400 000
C) $200 000
D) $0
E) -$200 000