The answer is "b. negative reinforcement".
Negative reinforcement happens when a specific stimulus is expelled after a specific conduct is displayed. The probability of the specific conduct happening again later on is expanded on account of expelling/keeping away from the negative outcome.
Negative reinforcement can be a successful method to fortify the coveted conduct. In any case, it is best when reinforcers are displayed quickly following a conduct. At the point when an extensive stretch slips by between the conduct and the reinforcer, the reaction is probably going to be weaker. Sometimes, practices that happen in the interceding time between the underlying activity and the reinforcer are may be accidentally fortified too.