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

Multiple Choice

Refer to the accompanying table. Martha's opportunity cost of making of a pie 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 cake.
B) 4/3 of a cake.
C) 8 cakes.
D) 80 cakes.