Labor Units:
US - 1 clock - 2 labor units (lu)
US - 1 sofa - 5 lu
Germany - 1 clock - 3 lu
Germany - one sofa - 9 lu

According to the table, the opportunity cost of producing one clock in the us is _____ and the opportunity cost of producing one clock in germany is ____.

a. 5, 9 sofas
b. 4, 33 sofas
c. 5, 9 clocks
d. 2.5, 3 clocks