सेवा विपणन सिद्धांतों के अनुसार, किसी फर्म की बाजार पेशकश को मोटे तौर पर किसमें विभाजित किया जाता है?

Services are characterized by all of the following core characteristics, EXCEPT:

The 'SERVQUAL model' for measuring service quality was developed by Parasuraman, Zeithaml, and Berry. Which primary author is associated with it?