You purchased a chicken for $8 and then sold the chicken to your friend for $9. Several days later, you purchased the chicken back for $10 and then sold the chicken again to another person for $11. How much money did you earn?

Three students try to answer the question.

Student A:

You purchased a chicken for $8 and sold the chicken to your friend for $9. You first earned $1. You then purchased the chicken back for $10. So you lost $1.

You sold the chicken again for $11. You earned $1.

In total, you earned $1 - $1 + $1 = $1.

Student B:

You earned $2 because you earned $1 each time the chicken was sold.

Student C:

Your profit was -$1.