Dana, Who Is a Trained Yoga Instructor, Spends 4 Hours

Multiple Choice

Dana, who is a trained yoga instructor, spends 4 hours on Monday baking and packing 10 boxes of cookies. She sells the cookies for $10 a box. Given that she can also teach yoga for $80 an hour, what is her opportunity cost of baking cookies?

A) $320
B) $100
C) $220
D) $420
E) $800