4. Suppose the Levee Blue Jeans® company uses excessive quantities of Cheap Blue Dye® in the production of its new, hip line of Irritatingly Stiff Jeans®. If the wholesale cost of Cheap Blue Dye® increases, which cost curves will shift upward for Irritatingly Stiff Jeans®.

As more pairs of Irritatingly Stiff Jeans® are produced, more Cheap Blue Dye® is needed, and vice-versa. Thus Cheap Blue Dye® is a variable cost and will only shift curves which include a variable cost component. These are AVC, ATC, and MC.

1. Average fixed cost. Since Cheap Blue Dye® is a variable cost it won't shift the AFC curve
2. Marginal cost and average total cost. Both these curves will shift but since this answer doesn't include AVC we keep looking to see if there is a choice that does. If no such answer is found we can come back to this one.
3. Average total cost, average fixed cost, average variable cost and marginal cost. Since Cheap Blue Dye® is a variable cost it won't shift the AFC curve which is included in this list.
4. Average total cost, average variable cost and marginal cost. This answer includes all the curves we've studied which have a variable cost component and none of the curves that don't, so this is the best answer of all give.
5. Average total cost and average variable cost. Both these curves will shift but since this answer doesn't include MC and since the answer above does this can't be best.