Refer to the Given Table A)an Increase in Supply

Multiple Choice

Refer to the given table. Relative to column C, column D represents: $$\begin{array} { | r | r | r | } \hline \text { Price Per Unit } & \text { Columu A Units Per Year } & \text { Colum B Units Per Year } \\\hline \$ 20 & 50 & 40 \\\hline \$ 30 & 60 & 50 \\\hline \$ 40 & 70 & 60 \\\hline \$ 50 & 80 & 70 \\\hline \$ 60 & 90 & 80 \\\hline\end{array}$$  

A) an increase in supply.
B) an increase in demand.
C) a decrease in demand.
D) a decrease in supply.