In an eight-hour day, Isabel can produce 15 pounds of taffy or 3 pounds of chocolate chip cookies. In an eight-hour day, Ramona can produce 6 pounds of taffy or 6 pounds of chocolate chip cookies. The opportunity cost of producing 1 pound of chocolate chip cookies is:_________
A) one-fifth of an hour for Isabel and one hour for Ramona.
B) one hour for Isabel and one hour for Ramona.
C) 5 pounds of taffy for Isabel and 1 pound of taffy for Ramona.
D) one-fifth of a pound of taffy for Isabel and 1 pound of taffy for Ramona.

Since Isabel takes 1 hour to produce 3 pounds of chocolate chips, it would take 1/3 of an hour to produce 1, no one-fifth of an hour nor one hour. Thus, options A and B are incorrect.

Now, in 1 hour, she can produce either 3 pounds of chocolate chips or 15 punds of taffy, thus, if she produces 3 pounds of chocolate chips, she could have produced 15 pounds of taffy. We can use a rule of three to determine that if she produces 1 pound of chocolate chip, she could have produced 15*1/3 = 5 pounds of taffy. Producing one pound of chocolate chip has an opportunity cost of 5 pounds of taffy for Isabel.

Similarly, Ramona produces the same amount of taffy than chocolate in one hour, thus, if she produces 1 pound of chocolate, she has to pay an opportunity cost of 1 pound of taffy.

Therefore, option C is the correct one.