-Refer to the Graph in the Exhibit

$$\begin{array} { | c | c | c | c | } \hline { \text { Poland } } & & { \text { Canada } } \\\hline \begin{array} { c } \text { tonnes of } \\\text { wheat per day }\end{array} & \text { t-shirts per day } & \begin{array} { c } \text { tonnes of } \\\text { wheat per day }\end{array} & \text { t-shirts per day } \\\hline 20 & 0 & 100 & 0 \\\hline 18 & 80 & 90 & 100 \\\hline 16 & 160 & 80 & 200 \\\hline 14 & 240 & 70 & 300 \\\hline 12 & 320 & 60 & 400 \\\hline 10 & 400 & 50 & 500 \\\hline 8 & 480 & 40 & 600 \\\hline 6 & 560 & 30 & 700 \\\hline 4 & 640 & 20 & 800 \\\hline 2 & 720 & 10 & 900 \\\hline 0 & 800 & 0 & 1000 \\\hline\end{array}$$
-Refer to the graph in the exhibit.What is the opportunity cost of 1 tonne of wheat in Poland a! ?

A)  10 t-shirts-b! 
B)  20 t-shirts-c! 
C)  30 t-shirts-d! 
D)  40 t-shirts