-Agnes Can Produce Either 1 Unit of X or 1

$$\begin{array} { | l | c | c | } \hline & \begin{array} { c } \text { U.S. production } \\\text { possibilities }\end{array} & \begin{array} { l } \text { France's production } \\\text { possibilities }\end{array} \\\hline \text { Steel } & 100 & 25 \\\hline \text { Concrete } & 200 & 100 \\\hline\end{array}$$
-Agnes can produce either 1 unit of X or 1 unit of Y in an hour, while Brenda can produce either 2 units of X or 4 units of Y in an hour. The opportunity cost of producing a unit of X is

A) 1 unit of Y per unit of X for Agnes and 1/2 unit of Y per unit of X for Brenda.
B) 1 hour for Agnes and 2 hours for Brenda.
C) 1 unit of Y per unit of X for Agnes and 2 units of Y per unit of X for Brenda.
D) 1 hour for Agnes and 1/2 hour for Brenda.