Refer to the Following Table Showing a Monopolist's Demand Schedule

Multiple Choice

Refer to the following table showing a monopolist's demand schedule:
$$\begin{array} { c c } \text { Price } & \text { Quantity } \\\hline \$ 50 & \mathbf { 3 0 0 } \\40 & \mathbf { 6 0 0 } \\20 & \mathbf { 8 0 0 } \\10 & 1,000\end{array}$$
-If price falls from $20 to $10, then

A) MR =-$10, and demand is inelastic.
B) MR = $10, and demand is elastic.
C) MR = $30, and demand is elastic.
D) MR = -$30, and demand is inelastic.
E) none of the above