Problem: Christkindlmarket is a holiday market that takes place every December in Chicago. From fresh baked goods to warm, sugary almonds, Glühwein to ornaments, the market brings holiday cheer to the cold winter months. Interestingly, any time a customer tips a vendor, the vendor is known to ring a bell loudly for everyone to hear. What sort of motivation does this describe? Question options: Positive punishment Positive reinforcement Negative punishment Negative reinforcement Pavlov's human response