Of the Following Scenarios, Which Is the Best Example of Negative

Of the following scenarios, which is the best example of negative reinforcement?

A) The teacher makes John stay in his seat until he finishes an assignment while all the other children are allowed to play.
B) The teacher scolds John for not finishing an assignment, then collects it and lets him play with the other children.
C) The teacher lets John play with the other children before he completes his assignment, but then asks him to finish it the next day.
D) The teacher gives gold stars to the first few students who complete an assignment during class.