Refer to the Accompanying Table A)3/4 of a Pie

Multiple Choice

Refer to the accompanying table. Martha's opportunity cost of making a cake is: $$\begin{array} { | l | c | c | } \hline & \text { Time ta Make a Pie } & \text { Tirne to Muke a Cake } \\\hline \text { Martha } & 60 \text { minutes } & 80 \text { minutes } \\\hline \text { Julia } & 50 \text { minutes } & 60 \text { minutes } \\\hline\end{array}$$  

A) 3/4 of a pie.
B) 4/3 of a pie.
C) 6 pies.
D) 60 pies.