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